Welcome to the community,
Here are some answers...
1. I think RPM's, for now, are good enough for you. If you need to build rpms from source, you would have to read up on it before you can start doing it. Whereas packaged RPM's give you a freedom to just install it. I would also recommend you use APT-GET or YUM so you can avoid so called RPM hell. Google on it and you would know. i386 rpms run on all machines upwards and including i386 which means they run well on i386, i486, i586 and i686.
2. You are probably talking about kernel compile. Although the kernel that comes with RedHat has optimization for your systems and you may not need exact optimizations so long as you are extremely picky about it. If you want you can always compile a kernel on your own but before that you need to know what all hardware you have in order to compile driver support for it in your kernel. Kernel compiles for newbies can be tricky and you are bound to have a couple bad compiles. There are many kernel compile how-to's on this site as well. Search on this site and google and you'll hit a mother load
. As for a beginner you are good with default system...learn about your system and linux in general and then dive into source and kernel compiles.
3. The Linux Documentation Project website, www.tldp.org