The Rail Pass I can help you on.
The pass is for JR trains and Shinkansens (bullet trains) for unlimited use during its validation period. It is not good for non-JR trains or subways. If you plan a lot of travel between cities, it is a good deal (i.e., Osaka to Tokyo, etc.). Otherwise, if you are just going to be in Osaka, it is probably not worth getting.
If you want to get the Rail Pass, you go to an authorized travel agent in your home country to purchase a voucher. You take the voucher to a JR office in Japan and exchange it for the Rail Pass. You can stipulate the date you want your Rail Pass to start.
If you are only visiting Japan as a tourist, going alone is no problem. I've gone there 4 times solo (and once with a group tour where I knew everybody as I was one of the organizers) and it was never a problem. It also helps having friends in Japan, which I do. Have fun!