Carbs: what about some of the used places, like re-psycle.com or possibly Bob's BMW.

As for batteries, I personally like the lead acid batteries. I've run Yuasa batteries in my /7 for years and am now on a Mareg from BMW. I'll probably go back to the Yuasa or Interstate next time around. People rant and rave about the Odyssey series, specifically this:

http://www.odysseybatteries.com/battery/pc925l.htm

The terminals are on the side...possibly there are tabs or something to all for standard attachements. Not sure about the physical side. I know that some batteries are too tall for the tool tray or too thin which means that some padding has to be used to keep the battery solidly in place. Snowbum has a page on batteries and also references Anton Largiader's website:

http://bmwmotorcycletech.info/newbattery.htm

Proper tires would be 3.25x19 up front and 4.00x18 in the rear. People tend to go with the metric equivalents but that will change the handling, although it might be hard to tell. I can vouch for the fact that metric tires are not as tall and changed how the sidestand worked on my /7. By being lower to the ground due to a smaller tire diameter, my sidestand was virtually unusable as the bike sat nearly vertical when on the sidestand...more than once, that bit me when the bike fell over.

Continental still makes the proper tire, as I believe Metzler. I'm running a 4.00x18 Avon Roadrider AM26 on my /7. So far so good.