Fiberglass experts; need help with project

I'm planning on making fiberglass covers for some engine and misc. body parts, nothing big, and need to know if what I've researched may be TMI. Never having worked with it before, I trolled the web and was not disapointed. However, everything seemed to be geared towards making molds for duplicate pieces; I'll be using the actual pieces as the molds. Onto the questions:

- considering this will be my first time, and one-offs, will auto parts store products work? Nothing will be subjected to much stress/heat.
- making molds for long term use was way too much work; is there a quick and easy way to prep the parts so the glass doesn't stick?
- everyone in the videos kept hammering the point home about having the part perfect before making the mold; one part I'm covering will definetly not be perfect no matter how much I sand or fill. Can I still get smooth-ish results somehow, maybe by just using the outline of the part?
- considering I'm on a tight budget, and the parts will not be show quality (that comes later, after more experience) can I get good results without a spray gun? Seems like every car show I watch that had a segment on fiberglass always used disposable/cheap materials and had good looking results.