alright..i'll do my best

1.) It's not MANDITORY to rebuild your internals. It's recommended because you can rev longer (or in boost longer) thus geting more power from your SC. Any type of forced induction puts more wear/tear on your internals. It's not MANDITORY, just RECOMMENDED. I wouldn't really worry about it now. I'd just look into it later.

2.) The only guage you'd really NEED would be the boost guage. It's always good to know how many lbs. your pushing. Then you can see if something is wrong (if you aren't pushing what your supposed to). Although the other guages would be somewhat helpful, they aren't really needed. The temp. guage is what i'd recommend after the boost.

3.) No SC don't need intercoolers or have blowoff valves (to my knowledge) I'm sure you could rig a intercooler to one with some modification, but it's not needed. Maybe with another brand of SC?? My friends JRSC was watercooled. I don't know if they all are, and I'm sure someone will elaborate on this.

4.) JR oil cooler: This is a pretty nice kit. I'd recommend it. My friend that has a JRSC has JR everything (he wanted to get sponsored) and he said it worked rather well. Especially under race conditions.

Hope that helps. I brushed on most topics, but that will get you started. Let me know if you have any more questions/comments.