There's a line about halfway up that you should use as the fill line for this style.
That;s the easy question.
The second part is more difficult. Depending on your yeast health and amount being pitched, plus temperature, you can see up to 3 days delay in fermentation taking off. Some people, especially newbies, sometimes never see bubbling - this is most likely due to the seal of your bucket being off. Even this is nothing to worry about - the pressure inside is keeping things out for the duration of primary.
With good yeast pitching rates, good temperature and so forth, you can see bubbling in 8 - 12 hours sometimes.
There is a good sticky at the top about fermentation taking off 48+ hours (don't remember the exact title offhand.
Personally, I will just shine a flashlight through the top of my fermenting bucket a day or 2 in, and if I can see a ring above the "waterline" inside, I know things are going well and not to disturb it for a couple weeks plus.