[Dearth]

All rock will have hitch hikers of some sort you will find many additions some good some not so good

If the worms are grey or grey with a red tip they are harmless bristle worms they are a good part of your CuC however once you have them almost impossible to completely remove from your system. I don't like them myself but kinda learning to live with them.

As to aiptasia you have a couple of options as I previously stated you can get peppermint shrimp which are relatively cheap, you can remove and cook the rock but not a guarantee to fully remove unless you cook it properly and it takes a lot of time, manual removal but that is hit and miss.

As others stated get some power heads in there it will help a lot and stir up the detritus

Canister filters are ok in a smaller system but they are a lot of work and honestly getting a skimmer will cut your workload so much

Most importantly don't rush take your time and ask questions if your not sure and take time to enjoy it you will get so much pleasure from it