I would think that even coarse vermiculite would clog up over time. Hydroton clay pebbles would probably be best for your ebb & flow. Any ph-neutral gravel would work. There are a ton of products sold for the purpose, like rockwool, coco coir, and 'sure to grow' media. Everything has a cost, though.

Pond liners are a cheap way to prevent leaks. You can make your own table with composite decking boards screwed to the common white plastic table you see everywhere.

Most sump pumps would be too big, I would think. Look for a "water transfer pump." They are smaller and cheaper.

I went with black heavy duty plastic to line my ebb n flo system. it is way cheaper than pond liner even after I doubled it up.
Another option for media is lava rock. pretty much the same material as hydroton buyt processed differently. just make sure to double up your liner if you do as they'r kind of abrasive. right now I have lava rock in one gallon pots and coir in one gallon pots in ebb n flow. I don't even use a pump, just pour in the nutrient in the morning and (maybe) in the evening and let it drain back into a matchin bucket. My system, currently holding 15 pots with 21 max only requires about two gallons to adequately flood the system. the trick is keeping the drain cycle slow so the pots have time to draw up enough moisture.
If you grow all those together in one reservoir, be sure to mix your nutrients for the peppers.

A small pond pump, that is a submersible type would work.