Zing, I second the motion that you should visit www.graflex.org and work your way through the FAQs.
There are, practically speaking, two models of 2x3 Speed Graphic: Miniature Speed Graphic, 1938-1946; 2x3 Pacemaker Speed Graphic, 1947 - 1963 or so. These two have focal plane shutters. There are also two similar cameras without focal plane shutters: 2x3 Pacemaker Crown Graphic, 1947 - 1963 or so; Century Graphic, 1949 -1970. I mention them because people, especially eBay sellers, use the words "Speed Graphic" very loosely.
The Mini Speed uses a stepped wooden board. I've never needed one, but people insist they're easy to make. Pacemakers, including the Century, use a metal board with a lip. One source for them is www.skgrimes.com.
The Graflok back was introduced in 1949. The Century Graphic has an integral Graflok back; 1949 and later 2x3 Pacemaker Graphics offered the Graflok as an alternative to the standard spring back. Graflok backs were sold for retrofitting to earlier 2x3 Graphics. All of the backs for 2x3 Graphics interchange; I removed the Graflok now on my 1947 2x3 Pacemaker Speed Graphic from a Miniature Speed Graphic.
Graflex offered 2 1/4 x 2 1/4 (6x6), 2 1/4 x 2 3/4 (6x7), and 2 1/4 x 3 1/4 (6x9) roll holders to fit 2x3 Graflok backs. These holders can't be used with a spring back.
There is, though, a 2 1/4 x 3 1/4 (6x9) roll holder that slips in like a sheet film holder and can be used on most, if not all, 2x3 press cameras with spring backs. Also on 2x3 Graphics with Grafloks. This is the Adapt-A-Roll 620. It was made for 620 film (same film and backing paper as 120, but on spools with narrower axles). The AAR 620 will feed perfectly well from a 120 spool but must take up on a 620 spool. I use AAR 620s because they will give 9 shots per roll instead of the usual 8 if loaded carefully. Since 620 spools are uncommon, I respool exposed film on to a 120 spool before sending it to the lab. That's what changing bags are for.
There are no sources for 2x3 color sheet film. If you want 2x3 color sheet film, you'll have to cut down a larger size. Just use roll film.
Good luck, have fun,