Do I need doors

So I can get a great deal on a totalled VW that is relatively new that is missing the passenger side doors.  I figured a roll cage and some lexan solves my door problem

1.  I won't comment on weather its legal or not to have doors, you WILL want doors on the car thats for sure.  As far as the hood, its not needed I have seen a few cars run without them for better cooling/to look more crappy.
2.  Most people run the stock tank, as many folks have said if you DO run a fuel cell make sure its in good working order and its a quaility fuel cell.  Same holds true with the stock tank and the rest of the fuel system, there is a reason fuel system parts don't count towards the $500 get it in good working order.
3.  Id say MOST people do something to upgrade the brakes on the car (better pads, DOT4 fluid, etc..)  it all depends on the car.  Teams running cars that came with decent brakes from the factory can usually get away with just running new brake parts.  Cars that came with crappy brakes from the factory (like our Camaro) need to do a bit more.  We ran better pads, new calipers, brake ducts, braided hoses, and all new parts in the rear (drums) and the brakes lived the entire race at Nelson Ledges.

I dunno what type of VW you have, but Id be willing to bet that better pads, new rotors, and DOT 4 would be just fine for most Lemons VW's.

Fixed:

I kid, I kid. (Rob, you have to admit you smiled.)

In addition to intrusion protection, consider driver access (helping driver in), driver egress (driver GTFO), fire (maybe a few extra seconds to GTFO), and rain.