More Pond Questions

I feel like a sub-moron in this pond building business. I cannot find
anything as to precisely how to connect the pump to the piping or hose.

One end screws into the pump and has an adapter which turns into about of 2"
inch flexible (?) pipe about a foot long. Believe this is called the pump
discharge. I know I will need to attach a 90 degree elbow to the pump
discharge too get the water out of the side of the skimmer.but how so that
it can be easily detached.

But then something is said about a check valve. And also removing the pump
in winter. So how can I attach the hose/pipe to the pump or pump discharge
so that it is easily detachable.

I had no trouble at all building my first pond but I didn't have all these
gadgets like filters and skimmers. The filter was a little external thing,
had never heard of a skimmer, and the pump simply sat on the bottom of the
pond with clear hose attached that connected pump to filter. Piece of cake.