It sounds like you live in an almost semi-rural environment. I can not say statistically that such dwellings are more, or less, targets than very isolated or urban homes. But being on a main route means that you have more traffic than the very isolated rural homes, and more people - good and bad - "just passing through". This means more exposure, and anyone with the wrong intentions has a main thoroughfare to make an escape.
The first thing to do is establish what additions or modification you can make to the house. Ideally, a home should be such that anyone can not break in with causing enough noise to wake up everyone at home, and sufficient enough that even with some substantial tools it will take them a minute or more to actually get inside. This is a tall order for some people, and in any case is a matter that can only be decided by those in charge of the household. In this case your parents.
Window and door alarms can be fitted quite cheaply, but can be a nuisance if everyone isn't familiar with their operation and consistant in their use of them.
Lighting is very important, and might be your way to break the opening subject with your parents, seeing as they see some significance in leaving the lamp on in the living room.
The exterior lighting of a house is very important. Floodlighting that faces away from but lights up all areas around the house right up to the walls will enable those inside to see what's going on outside. They can be left on at night to discourage intruders, or they can be activated if there is something going on outside that causes suspicion, or they can be sensor activated.
Inside lighting can be installed that can be used to light up common areas inside the house from remote switches in the bedrooms. These flood or wide spotlight should face away from your bedrooms so that they illuminate the common areas, making it difficult for any intruder to see you, and making them clearly identifiable and easy targets.
I think lights mounted on long guns or handguns are a bad idea. For one thing, like all electronic gadgets they rely on batteries, bulbs and switches which although very reliable when put together and maintained by the right people, can and do fail at the worst of times. I have a pile of lighting devices both cheap and expensive for various purposes; if I am investigating something potentially unpleasant at night I certainly have one with me, but I may not always want it switched on. And I certainly do not want to rely on one to defend myself even in near darkness. If it happens to switch on accidently - because of some unforseen activity, or a faulty switch - I want to be able to toss it immediately. Any lighting device is going to reveal your presence and location to all and everyone for a considerable distance. To use a gunmounted light to identify a person as friend or foe you must point the weapon at them, which violates Rule Two. Of course you can point it off to one side, but to gain the advantage of some spotbeams one has to pretty much point the muzzle at what you want to ID.
I disagree with those who say to just call the police and wait. For one thing, the police are going to, at some stage, ask you to come out and meet them. Few peace officers are going to attempt to enter a house on a call from an unidentified person (regardless of what is said over the phone) of a break-in. You can by all means call them, but at some stage you are going to be faced with the same practical problems. And on their arrival the now additional factor of making sure they do not mistake you for a badguy attempting to leave the scene, or in the event any shooting starts you may find yourself in the line of fire from both the goodguys and the badguys.
First you need a plan.
For all likely occurences. You can not plan for everything that might possibly happen, but those that commly and might reasonably occur. As you learn more, this knowledge, and your planning etc can be expanded.
In your circumstances, depending on who is at home at the time, your plan should run something like; make ready, pick a vantage point where you can see and hear as much as possible (but a defendable position) and listen, look and evaluate for at least long enough to know whether it is in fact a person inside the house, or something else. Be ready at all times just in case an intruder appears suddenly, and maintain a cool fighting mindset. Many people have a problem maintaining "cool"; but it is imperative in making accurate judgements - you do not want to shoot a member of your own family who has arrived home early from a "vacation", or who got up to make some hot chocolate and dropped a porcelain mug on the kitchen floor.
In general, it is clearly an intruder, your best tactic is to let them come to you. This gives you the advantage in almost any likely circumstance. If you hear no further noise after being initially alerted, and a substantial period of time elapses - say three to five minutes - then it is probably time to move. One short slow step at a time, as noiselessly as possible. Use your peripheral vision, especially when entering opening areas of the house.
In your planning, go through the house at night, and make notes on every reflective object and surface that gives you otherwise obstructed views of each room and area. Write them down, memorize them, keep track of changes. Maybe hang a few extra pictures (parents permitting), buy them a shiny brass vase, maybe an antique mirror, whatever fits where, and you can afford, that will assist in viewing critical areas from concealed positions.
Equipment.
I usually prefer a long gun to any handgun even inside a dwelling. The reason is that handgun cartridges are very poor stoppers - regardless of caliber or bullet type. However, a handgun is ideal for wearing around home (not all break-ins happen when everyone is tucked in bed - or even at night), and they are a back-up weapon in the event of a long gun malfunction. Ammunition is a deep subject that is well-addressed in other threads.
I do recommend clear wraparound type shooting glasses. many injuries in armed confrontations are eye injuries. Any time bullets are flying in an indoor enviroment the potential for flying glass fragments, wood splinters etc is quite high. Good ones are not expensive, and there is really no reason not to wear them.
While I generally encourage people not to rely on gadgets, one potentially beneficial item is the electronic hearing protection that amplifies normal sound, but suppresses damaging levels (like gunshots indoors). I do not have these, but the idea has great merit. The worse thing that can happen is that they "fail" - you shed them on the spot - and carry on. The sound amplification would aid greatly in evaluating and tracking any intruder inside a home, and possibly save some hearing damage if shots happen to be fired.
These points are just a start. As you read more material and opinions it will feed your own intellect and you will develope ideas and refine plans of your own.
) but good ideas are hard to come by. The intercom comment gave me this idea: hit intercom on a phone (preferably one that wont ding and need to be answered) so I can hear whats upstairs from down here. And at the top of my steps I can see pretty well thru the house. except not my neices room. and if you havent seen by now, thats my biggest concern. I'll keep pondering