jared patton

Good afternoon.
I have owned my civic for about 10 years, most of which i could not legally drive, now that i can i would like to upgrade the hell out of it.
I am curious what any knowledgeable people would suggest for good sites to buy parts off of, and any good suggestions on engine and transmission upgrades.
I currently have a 4 speed manual, and would like to move to a 5 speed, but would also like to potentially upgrade the engine to be a bit quicker.
Both run very well for its age and mileage so its not too high on my list until i get some of the other items.
Everything else has basically been replaced, mechanically, with the exception of the rear suspension and cosmetic items.
My interior was in great shape until i realized moisture has been accumulating under my rear cover above my spare tire and has been growing mold, which has spread to my backseat.
Now it appears i will be replacing most of, if not all, of my interior, and its a shame because the grey leather is in near perfect condition except for my drivers seat.
Any help with some of my issues would be GREATLY appreciated.
Thank you for your time.