The Anderson/Warm/? connectors come in two basic SIZES, large and small. Each size comes in different current ratings however. The only difference is the hole that the wire goes into in the end of the actual connecting pieces. When making the connections you should solder the wire in, (use resin core solder) rather than trying to crimp it. If you solder you get a much better connection plus you can always re-use them elsewhere if you want to change something.
If you buy the largest current rating for each size, then you will always be able to get your wire into the hole, and since its soldered it doesn't matter if the hole is oversize.
Either way, when you make the final assembly, squeeze some dielectric grease onto ALL the metal parts, even any exposed copper wire to prevent corrosion.
Most people find the rubber protective plugs a PIA as they don't work to keep mud/salt/ice out. They might keep little fingers with screwdrivers or other stuff from "gumming up the works" however....