Having sold many different types of sharks in my career, I have to say that I am not really happy with many of the sharks I've sold being in fish tanks of any size. Any shark that gets to an appreciable amount of size really does not belong in a fish tank. ( IMO
to be politically correct. )
With that being said, many of the cat sharks ( banded, Epaulette, spotted, etc) I've sold had long lives (to my knowledge) and are probably better suited to aquarium life as they are not really active swimmers and most only get to about 4 foot in length. The big thing is to make sure you have plenty of bottom space for them to swim when they want and hiding areas in the decor for them to hide in without getting scratched up. Soft sand should be the bottom substrate. Since there are a number of varieties and these sharks tend to not be territorial, a small collection is possible in that sized tank with the right filtration and decor.
As for the shark egg question, most often, the shark inside the egg is a banded cat shark however, we used to also get horn shark eggs which looked like a large drill bit which "unscrewed" a bit as the fetus grew and eventually popped out the top. It's an amazing thing to watch the embryo develop then hatch. We also used to run "guess the hatch date" contests for our customers for store gift certificates with just bragging rights for the employees who guessed right.
With the current population crisis of sharks world wide, serious thought should be placed into a proper set up for any shark you may get as every one that is taken from the seas and dies from our neglect makes that species one more specimen closer to extinction. ( Don;t mean to be a downer but shark populations of most species are in serious trouble. Keeping any shark in a tank should not be taken lightly. IMO
Hope this helps.