I am reclassing to 46R from 31B. Will have to leave my wife behind or will we be able to stay in a hotel at Ft. Meade?

46R is a single phase 15 week class. You will attend in a TDY enroute status. You'll receive your follow on assignment no later than 60 days prior to your course start date. Once you receive your orders to your follow on station, your levy brief will explain the different ways of moving your family. For instance, moving them ahead of you or returning to clear.

Look at the DINFOS web site for student info. I happened to look at it yesterday and suspect you will be required to live in barracks.

There are a lot of things you can do if command sponsored. However I have never seen a command sponsored tour for less than 6 months (at least for us below O-6 / 7 drones. Unless you are independantly wealthy she may have to stay the 15 weeks in a no-tell motel which isn't at all safe. Listen to "Top" below ... mine always kept me out of trouble.

Probably not

Assuming the welcome letter for Army is still current, you will be in barracks even as an MOS-T. Usually the only occasion you do not live in barracks is if they're above capacity. Very likely it will be barracks so I'd go with what SFC Boyd said in his response.
http://www.dinfos.dma.mil/Student-Info/Service-In-processing/Army/