Welcome to the SpyderHood
:congrats: & :welcome:
You've found the BEST place on the World Wide Web for anything & everything Spyder Related. While I can't answer your questions from experience, I can offer my opinions from experiences from this site & ryding with other Spyder Ryders.
1: Being on the L A R G E R side, with a passenger, you DEFFINATELY want to be looking at the RT model, as it itself is a bit larger than the RS model, and offers more comfort for the ryder & passenger.
2: If you have many years of prior MC experience, keep in mind, a Spyder is NOTHING like a traditional 2 wheeler, more like a quad or snowmobile, so please, for your own sake, don't try to ryde it like a traditional bike, or you will end up frustrating yourself. Light grip on the handlebars, squueze the seat pads with your knees to help hold on, lower your center of gravity & learn INTO the turns, most of all, relax & enjoy the ryde.
3: No silly questions here. You may want to check on the forum under your state & see if their are any local ryders in your area that can maybe give you feedback when it comes to dealers. Word of caution, the closest dealer MAY NOT BE THE BEST DEALER & proper dealer set-up of a new Spyder can make or break your Spyder Experience. If you can get feedback from other locals, PLEASE, do yourself a favor and take it. There are some dealers from hell out there & we don't want you to have a bad experience.
4: As for room, I have nothing to offer, other than I'm sure some of our other more well fed members may chime in soon to give you their feedback & opinions.
Good luck, & you've come to the right place for research. Hope all goes well

ray::thumbup:
dav n ted~