Use an aquarium or hydroponic supply pump, sump isn’t what you need, and aren’t for continued use.
There’s a lot of different opinions on flooding, but 15 minutes 2-3 times a day is good. In heavy flower you will probably will have to flood 3-4 times a day since the plants are consuming more nutrient solution. This’ll depend on a lot of factors, chiefly what substrate/media you choose, how big the plants are, etc. In a roundabout way, you’ll flood enough times to keep the media moist. Flood height should be about halfway up the pots. So if you have a pot that’s 8" high, flood about 4" high.
If you use big pots and a lot of media, you may only have to flood 1-2 times a day. The more flood/dry cycles and the more air in the media, the faster/heavier your rate of growth, but also a lower margin of error, such as if a pump fails and the plants need a flood cycle every 3 hours you could be looking at dead plants in less than a day. Using more media and less flood cycles means they don’t dry out as quickly and thus you have a greater chance of catching a failure.