Can't speak to the mirrors other than to say that on mine there is a nut on the underside, but the mirror stalk isn't threaded all the way, so I would think you might have to add a flat washer or two under the nut to get things tightened properly.
As far as storage, first, I would run all the corn polluted gas out of the tank and do the last couple of fills with premium corn free gas. Add a gas stabilizer like Stabil following directions on the bottle. Do all of your fluid changes, especially the DOT 4 in the brake system. Clean the bike and dry it completely. If you don't plan on doing any work on it over the winter spray all the exposed metal with a corrosion preventer to protect it from the salt your wife's car brings into the garage. The S100 guys make a good one.
I leave the battery on the bike over the winter. I have a trickle charger I got on eBay for $14.95 that I plug in once a month for a day or two. This lets me fire it up every couple of weeks to circulate the oil. Let it run for 3-4 minutes so the head and exhaust get hot enough to boil off any condensation.
Last, put the bike up on the centerstand, and if you are really anal, put a block under the final drive to take the weight off the rear tire(you did check the tire pressures before storing). I have a cheap nylon cover, again from eBay, that I throw over the bike to keep the dust and whatnot off.
I keep my insurance active all year so that in the event a dry day with temperatures above freezing comes along I can get out for a ride which is the best way to keep a brick ready for next year's riding.
