EAA, PFA should have plenty of information on homebuilding. Yes, you can do it in your average car garage (dual garage being recommended) as long as you can maintain the environmental standards that apply to the type of building material you're working with (glassfiber/resin being the strictest in terms of temperature and humidity).
Two books to recommend:
Choosing your homebuilt - Kenneth Armstrong
Kitplane Construction - Ronald J Wanttaja
As for paperwork: Just the parts receipt will not be enough. During the build you will have to have regular inspections by an inspector - that's where the EAA (US), PFA (UK) or similar organization comes in. These inspectors are there to satisfy that your building meets the standards, particularly since after the build a lot of your work will not be visible anymore. Also, you've got to find a way to prove to your inspector/the FAA or CAA that you built the plane yourself for a large part (500 hours or 50%, depending on FAA or CAA, I don't remember which is which) so usually people keep detailed logbooks with photos etc.
When finished, you will be limited to Day VFR only, and only private flights, no aerial work etc. Only in exceptional cases does the FAA (and only the FAA) allow night VFR or IFR flights in a homebuilt.
So, if you're serious (and if you want to build a high-wing piper, I doubt that somehow
) your very first point of call should be the EAA or PFA. Decide whether you really want to build something, then what sort of plane you will want to build, what materials you want to use, whether you're going for a kitplane or plans-built, etc.
Best to buy and read those two books first, check out some websites of PFA, EAA and various kitplane manufacturers (Europa, Kitfox, Van's, Murphy, Jabiru, Lancair, Glasair, Zenair etc.), subscribe to a few mailing lists, sit on the idea for a year or so, consider the type of flying you do and the type of plane you need for that, consider your budget and available time, consider your expertise with the materials you're going to work with and then make a decision. Oh, and there are plenty of half-finished kits out there that can be picked up for a bargain. Guess why.