Help for a New Guy.

My name is Dave and I am new to forabodies, and somewhat new to classics. I fell in love with the Dart when I was 16. I needed a car and my dad hooked me up with a guy who sold me a 65 Dart with a slant 6 for $200. It was rusted, dented, terrible paint, interior falling apart....but it ran. I drove it for 5 years until the rust got into the engine compartment and could no longer even hold an engine. I always felt terrible about not fixing her up and as of yesterday I plan on gaining redemption! Yesterday I bought a 1965 Dart GT with a 273 and a two barrel. It is in fair shape but will require a little work from me! I do have a ton of questions though which is the purpose for this post in the first place.

The front and rear bumper are not proper so does anyone know where I can get the proper ones?

The drivers bucket seat is worn so should I get a new one or just have it redone?

There is some rust at the rear egdes of the rear wheel wells. How do I take care of this and are there any other common areas that I should be alerted to and/or check out?

It has a two barrel carb but the old upgrade did allow for a four barrel. Is this recommended, and if so, somewhat easy to change?

and last...a total rookie question...fuel? lowest grade? Highest grad? additives?

I'm sure there will be way more questions as time goes on. Sorry about the length here. Thanks for taking the time to read/answer and I hope to hear back some good thoughts. Thanks a ton.

-Dave