once in a lifetime trip

I have many questions;

Can you make the long train reservations online, before you activate your pass? We will need to do some long train rides within a few days of arriving.

Can one person use multiple rail passes in one trip? I will be in japan approximately 43 days and would like to use 2 passes one after the other.

As my birthday falls into this period, I want to go to and onsen with that fancy many course meal. Ideally for one night, and then spend the rest of the time at a cheaper ryokan in the same hot spring town and do day trips to other springs. Are there any hot spring towns which are both nice and accessible from the jr system? Any you would recommend? Preferably in Shikoku, Kyushu, or the south west part of the main island. Within a days trip to Fukuoka would be nice.

Any advice for traveling in japan would be welcome. I would of course be open to any suggestions on how to get the most out of this once in a lifetime trip. Particularly if you know of any websites which could help me find Japanese cultural events during this time. Also do you know how far out sumo matches are typically scheduled? I would like to catch a match.

as i will do a lot of traveling which of the other train cards are most useful? particularly around Tokyo, Osaka and Hokkaido?

than you for your time in answering these many questions,