Welcome to the forum. And congrats on buying the best car in the world.
Re your few problem areas, im sure the guys and gals on here will have all the answers for you. For myself id try to find an original radio rather than a after market one. Once you get it working you will find the sound quality is out of this world. Front seats take quite a while to warm up so might be working after all. Benfur, one of the forum members shouls have all the SH parts you needs like wing mirror. Leak in the boot is probably down to missing plastic bits over the rear lights. Open the boot, on each side of the opening just over the lights there should be a black plastic corner piece. If they have not been put back teh boot leaks. The exhaust manifold/cylinder head gasket is a pig to get to. The most likely place to find a blowing exhaust is the flanges between the cats and the "Y" pipe under the car. Its a common issue. Youll find loads of posts about it and ways to "fix" it. Dont know whats happenng with your fuel guage but the tank on a MK11 holds 85 lt or 18.7 Imp gallons.
Thanks for the response dude sorry to hear your having to sell yours. ive got alot planned for this baby as its a cheap car for the ammount of luxury i cant fault it. its going straight in for a black respray as its pearl white at the moment. Im thinking black car deep dish rims and a set of tints will have it looking the bollox. probably complete oposite from what most people would do to it but i think it will look nice. i just want to make sure im not investing in a can of worms that will be hindered by electrical issues before i start.
the heated seats in the front defo dont work as took a trip from birmingham to leeds and the two guys in the backs arses were roasting and me and the passenger were feeling nothing lol. so will need to over come that. but the gauge is the worst with it being the v8 u get a fright. one minute the guage is half full next its reading empty lol.
If anyone reading this is breaking an ls im after the radio and a wing mirror. id rather keep the radio origianl then the stack system works without any issues.
Once again cheers for the response.