If battlepoint bonus says it is for 2 hours, does it mean it gathers the points exactly in 2 hours of play time, or is it so that I receive bonus for the normal battle point amount even if I activate the booster 10 seconds before I win a match?
It only counts the actual game time the booster was active. So if you enable it 10 seconds before and that 10 seconds is 0.1% of the total match time you will get a bonus equal to 0.1% of that match. Likewise if the booster wears off it only counts for the minutes it was on. The booster only wears off by playing games that grand battlepoints.