No, two hours late won't make a difference. I would worry more about 6 or 12 hours.
There is no way to tell if you have ovulated. Ovulation does sometimes happen, and you can't tell if you have or haven't ovulated. The pill works in other ways, too, and your chance of pregnancy is still less than 1% even if you ovulate. Some pills (mini pills) don't even prevent ovulation at all, and they are still effective.
Theoretically, you have no menstrual cycle while on the pill. So no, it doesn't matter when you have sex, your chances of pregnancy are the same the whole time.The pill works basically by maintaining even hormone levels, and avoiding the ups and downs of your natural cycle. So no hormone changes = no cycle. At the end of the month, when you stop taking the pills, it triggers a change in hormones, which causes a "period." So it doesn't matter when you miss a pill, it just matters that you did miss a pill, because it will trigger the hormone changes that mimic your cycle. Once you miss a pill, you still will not ovulate if you just miss one pill necessarily.
So no, no days are safer than others. The only reason the timing of missing a pill might matter is because if you miss, for example, the pill before your period week, that would be more dangerous because you wouldn't get the hormones to make up for it.
I hope that helped!
