Hi John,
You are pretty close. Get Joyce Wilkerson's book Clownfishes and get answers to most all of your questions.
They need more than a clay pot to mate. It is not a mating que, but a convenient (for the aquarist) place to lay eggs. Joyce will fill you in.
Eggs are LAID in the daytime usually, and only hatch after dark. Perhaps that's what you were remembering.
Eggs mature and hatch to larvae. Either eggs can be removed from the tank before hatching, or larvae can be removed immediately after hatch. The parents will eat the larvae if left alone with them. The larvae need a tank devoid of predators to survive. Joyce will fill you in on the details.
No sure what you mean by hardest time. Losses can occur at any time, but usually most losses occur in the first 2 weeks.
We are often asked if it is easy to breed clownfish. I find that a difficult question. Everything is easy once you know what you are doing. If the question is: is it simple to raise clownfish?, then the answer is, IMHO, no.
Get Joyce's book, and enjoy reading it. You will find a lot of good information there, and can refer back to it when you need to.
Good luck, and check back with us when you get started.