It really depends a lot on feeding, but for a 100-120g tank the minimum size I would recommend is 2 cube/day or 24 sq in, and probably double that if you have a lot of livestock.
Pump size is going to be dependent on your choice of screen dims. The one that matters is screen width. 35 GPH of flow per inch of screen width is what you want. That's actual flow across the screen, not the rating of the pump. If you're using a dedicated pump, for estimation purposes I use 2' of loss for the slot pipe, then add the vertical rise and that will get you close if you are using a chart. For instance, if you have a 6" slot and 12" vertical from the water level of the sump to the centerline of the slot pipe, that's about 36" of head. A Rio+ 1100 will give you about 240 GPH initially (bare screen) and that will drop a bit as you get growth. A Rio+ 1400 will give you more like 300 GPH initially.