Up to now, the schedulers have been very flexible with the way we use our leave and days off. Basically, the 10+2+2 (commute days) are available each month of the fiscal year (April 1 to March 31). As long as you don't exceed these in 1 year you are OK. I have heard that the company will not give you commute days for a calendar month, if you take no days off in that calendar month.
What the future holds, who knows.
As far as the bonus goes, the FO bonus is frozen on the day you become a Captain and this amount is held until the original 5 year period is up, then it is paid out.If you leave before the 5 year period is up, you get nothing. On Captain qualification, a new 5 year bonus cycle starts.