Ok some things because I'm getting confused again...
There is no C1 FFL There are Title 1 guns, there is a Class 1 SOT but that's for an importer, there is a Type 1 FFL.
I am a Type 1 FFL and pay a class III Sot (Dealer in NFA firearms)
I am a Type 7 FFL and pay a class II SOT (MFG/Dealer of NFA Firearms)
I am a Type 10 FFL and pay a class II SOT (MFG/Dealer of Destructive devices)
You will be a Type 01 Class III dealer.
In reality if you FFL and SOT have the same EIN, you are probably a little better off but it doesn't matter that much.
Transfers, if you can get $150 for them that's pretty good..most will do them for under or around $100.
"approval" comes in the form of your stamp, it's good for a specific period of time, no prorating or deiscounts for parts of the year not used.
It will take about 1-2 months for your SOT to be registered in the system and for you to get at least a control number, if not the actual receipt.
As long as you have your FFL there is no real "approval" just administration and paperwork.
You have to pay your SOT every year, give it up at some point down the road, that's fine but make sure you transfer your samples out either to yourself as a pre sample or to someone qualified as a post sample.