It’s pretty common to see main drains tied to a skimmer as opposed to a direct line to the pad. It greatly reduces the chances of a suction entrapment since a body attempting to cover a drain would essential cause the pump to pull 100% from the skimmer thus relieving any suction pressure. However, from a hydraulic standpoint it basically renders the main drain useless as flow is greatly reduced. Given that split drains are standard code for pools nowadays, the main drain should really be plumbed directly to the pad but, as the saying goes, you can rarely teach old dogs new tricks.
A simple 1/2 HP sub pump, even a cheapo foreign made one, will be useful in many ways. If your home is prone to flooding, they come in very handy for moving water around. I got rid of my scuppers on the roof but, before I did, they use to create these large puddles around my house whenever it rained. The water would sit stagnant at my foundation for days after everything else was dried out and they became a source of mosquitos and termites. I would often run out and drain them using my sub pump just to keep the water away from my house. Now I use it for pool maintenance stuff and to drain a little fountain I have. I consider it to be a useful home tool to have around. I figure if I ever had a clogged bath tub, it would be fun to drain with the sub pump ...