If oyu're planning on mounting it to the sled, get a Ram mount. By far the best option out there for that. I mount my GPS on the dash of the sled, not the handlebars. I smash into the bars too much. Bar mount is the best way to go on a bike though.
I have a lapel spkr/mic with my radio, but that gets set up at the truck, key/dial lock go on, and it lives on my pack the rest of the day. I don't think the lapel mic would work well with the GPS as you're using the GPS more often and the additional cables just get in the way.
I'd go with the City Navigator DVD if you buy any maps. Far more up-to-date, contain useful POIs, and they have a lot of FS/dirt roads.
If the Rino has a 4-pin round, I'd use that and hardwire power to the sled. pfranc.com is a great source for that connector.
