Welcome! Nice bike! Not too many of that model floating around. And with the low seat, too.
Make sure you do a real good flush on the brake systems. They are often neglected, and old fluid is tough on the ma$ter cylinder$ and caliper$. You want to take a weekend to pull the transmission to clean and lube the clutch splines which will go a long way toward making the shifting, especially going down between 3-2 and 2-1 a LOT smoother.
Another thing about brakes, a lot of these bikes are going around with sintered pads. If it were my bike I would pull them and replace with new kevlar organic pads. They stop as well as the sintered but won't eat those stupidly expensive rotor$ anywhere nearly as fast. These are the ones I use:
http://www.ebay.com/itm/1989-1996-BMW-K75RT-Kevlar-Carbon-Front-Rear-Brake-Pads-/131516075180?hash=item1e9ef80cac:g:kasAAOSwhcJWHWAF&vxp=mtrThey squeal a little bit at low speed when they're new, so you want to put a little squeal stop or high temp brake lube on the back when you install them.
You can't go far wrong with the Shinko tires mentioned above. For the money they are the best deal out there. I have gotten 10,000 trouble free miles on a rear Tourmaster.
For oil changes, I have had real good luck with Carquest oil filters. Used them for over 20 years, and routinely get 200,000+ miles on my vehicles. Very good for the price. Ask for their cross reference to the AC Delco PF53. They use a different wrench from the standard BMW/HiFlo that are very common. I think it is a 74mm 15 flute. Buy it with the filter and check it at the counter. You should be able to buy the filter and wrench for less than a single HiFlo filter.
Good luck with your new bike, she's a beauty.