RXKEN

1. Really depends on the income level. Married couple is no different than filing individually.
Just if one spouse is low income, you may be able to claim spousal credit (non-refundable).
Some credits will look at both your income and determine who to claim the credit (eg. Child care expense)
Likely your benefit will be lower (GSTC and CCTB) because most of the case, 2 people's income is higher than one

2. I don't see anything regarding on $2500 student loan interest.
http://www.cra-arc.gc.ca/E/pub/t ... e.html#P1272_170813
you should be able to claim whatever amount you want but CRA may ask for proof
You can also carry it forward 5 years

3. Yes. Pension income spliting. Not working income spliting