My partner and I are looking for a trainer beginning spring 2012 in Vancouver, BC. Would like some tips.

Man or Woman?
What qualification to look for?
Anyone has trainer that manages diet too? Or dietician/nutritionist and trainer are usually two different people?
How much money is a right amount?
Home gym or commercial gym?
How long do you stick to one before deciding to hire him/her?
Can a couple train in one session at the same time?
Based on your experience, how many sessions per week?

Thank you for your advice.