A search would have answered most, if not all, your questions, but as it is the end of the year, I'll be nice (believe me, that's rare!

) and answer them.
Posted to base of choice? Not necessarily, some people do get lucky but the CF sends you where they need you.
How long is a posting? They all vary in length. I was at 2 Fd Amb in Petawawa for 10 years. Then only in Kingston for 2 years. Positions change along with promotions, training levels , etc.
Should you sell your house and buy one where you are posted? That also depends. Do you want to keep your original house for some reason? If you are going to keep it, do you have reliable renters? Can you afford a house at your new posting? There are too many factors in play here.
All in all, just worry about BMQ and trades training for now. The rest will come later. Here's a link for
Royal Lepage Relocation Services, which is who the military uses for postings.
Good luck on BMQ and Happy New Year! :cheers: