Your home resort is where they Welcome you Home.
Seriously, it is the
DVC location where you bought your points (DVC is a real estate timeshare) and it is the location that determines your annual dues, your RTU (years left on contract), and where you get priority booking at 11 months vs non-home resorts booking at 7 months.
Most people advise buying a home resort where you WANT to stay as it gives you a 4 month advantage with booking your trips there.
If you book your vacations at 7 months or less, then it does not matter where your home resort is.
The annual dues can vary a lot based on home resort from the lowest BLT $4.50 to highest VB $7.41 and this is probably the SINGLE most important factor in buying DVC as 30-50 years of dues will far outweigh a few dollars difference in the initial buy-in.
Also, YES you can have several different home resorts but they will be different contracts in the same (or different) membership number.
If you own 450 DVC points in one membership number in three different resort contracts of 150 points each (i.e. BLT, SSR, OKW) then you can have 150 point booking at each resort at 11 months or 450 booking at one resort at 7 months (assuming you dont borrow or bank)