leave the sound deadening man... sounds like u want a nice daily and for the 20 kg... it will work wonders
full bare metal will be a mad pain in the arse, but will give good results. however, if you dont mind a bit of extra elbo work, keep it acrylic and you will get a close result with better clarity than a 2pac without rubback.
engine bay would be worth using a heat resistant enamel i think?? im no expert and others here would have better answers, but the finish doesnt need to be awsome, but should be very tuff.
good luck mate.... im embarking on a similar thing soon so any tips you get shoot em my way lol
pat