A lot of good advice
There has been a lot of good defensive advice offered, tactical and legal. The only thing I have to add to that would be to (if you have the money) hire a security consultant (in addition to the lawyer) to advise what measures would be most effective in making your house safe. None of us here on the forum have seen your house, so cannot advise in defensible space, perimieter protection, best placement of detection devices, etc. (Dog, multiple layers of cameras, off-site storage, safe room with cell phone and independent power etc.)
What really prompts my post is to suggest taking a proactive approach. Find out who these guys are. Get an injunction against them if you can (was suggested already) and then go a little further. Without becoming a stalker or violating their rights/privacy find out what you can about them. That may give a clue as to how to get them prosecuted (maybe not for the crimes against you, but at least for SOMETHING).
Knowing some of their history, you may also get a clue as to who else might wind up targeting you. The fact they took pictures of your house's exterior indicates a great deal of planning and they may, having already been identified by the police, turn the job of your home's invasion to other criminals whose faces you don't have on camera.
I feel for your predicament. It is unfair that you should have to spend your time, worry and money to make you and yours safe, but that is the situation. As long as you are faced with this unfairness, you might as well get out ahead of the events.
Is there a victims' rights advocate in your jurisdiction? They may be able to help get extra police effor, since your burglary and continued harrassment/stalking is ongoing and apparantly escalating. It seems pretty clear you are being actively targeted and the usual advice of "Make yourself a less inviting target and the criminals with be discouraged and look elsewhere" is definitely NOT applicable. You are not a victim of opportunity, but an active target and the odds of an escalation are pretty near 100%.
So, point by point, my advice:
Contact (if there is one) the victims' services office with jurisdiction in your area. See what assistance/advice they have.
Consult a professional security specialist for how to harden your house. The same security specialist might have advice on what to do with the information of the next step.
Find out who these guys are and the people they run with and everything you (legally) can about them. This may start with an internet search of court records (usually public records, but with juveniles usually protected, but there are sometimes legal ways around that)
Get an injunction against them if you can. Or, find out what their beef is and if there is more to the story than you know, perhaps a truce could be negotiated. Or, at least, the knowledge might make you better armed against them in their criminal trials.
Consult a lawyer with two questions: 1) What are our rights with regard to self-defense? 2) Can I go after these guys with criminal charges or civil charges (in court) with or without the police? If you can find a lawyer in private practice who used to be a prosecutor, so much the better (my opinion). You want to find an attorney equally adept at 1) defending you if you should have to explain use of force and 2) figuring out how to gather evidence to prosecute or sue these criminals.
And a VERY BIG caution. These guys are not just burglarizing for fun and profit. You have been targeted and are now being actively hunted. Let that fact inform your decisions. I don't want to scare you, but if they are determined enough arson is not out of the question, nor is a hit on any of you in some other location.
Good luck. and prayers be with you. God helps those who help themselves, and remember, God is observing how you do that.
Lost Sheep
With regard to EarlG's advice. Forum rules forbid a specific response, but I gotta respond. I know the impulse is to gear up and go hunting, or as you suggest, set up with an overwhelming response team. Gratifying. But the fact is that private armies (or even just a fire team or two) is beyong the reach of most of us. Vigilantism 1) is not Legal 2) is too easy to make a mistake and get the wrong people killed 3) seldom the end of the matter (at least not satisfactorily).