FluvalU4 Underwater Filter, Freshwater and Saltwater Aquarium Filter, A480,Black

Currently have a 10gallon but will upgrade shortly to a 30ish for a yellow eared turtle. Does this sit on the bottom where it could suck in the food and waste that collects on the bottom where my river rocks are? It has proven hard to get that out and the pleccu is not cleaning it up as of now.

Does the U4 filter have space to add activated carbon pellets?

Do all 3 outputs work at the same time?

Can I change the direction of the water coming out of the nozzles? For example directing it upwards instead of horizontal.