If I disconnect battery to clean, what problems might I have?

Lose radio station memory. If your old battery is OE it may be shot, but it's more likely to have been replaced already. The negative terminal holds up well, but you scrub that pos one with baking soda/water and a stiff brush. Paint the stupid steel strap with a rust- proofing solution (Duro Extend et al) as well. I like the durability and value of COSTCO 25 (OE size) and 34 (bigger) Interstate batteries, by the way.

Oh...forgot...you may have to reset the front window auto-up function: raise pass window to top with its own door switch and hold button up for 2-3 sec. Then lower to fully open, again holding button depressed 2-3 seconds. Repeat with driver's power window. Both windows should now be fully operable both with their own switches and the driver's master. Small chance the rear hatch logic gets uncalibrated too. If so, fully open hatch (manually if necessary!); slowly force hatch down to fully locked position (you'll hear the double-click). Then actuate hatch button for normal operation (two beeps and auto- open). I think the 2 position seat buttons stay in calibration, but I forget....