If you're designing this plumbing system yourself, you probably can set it up so that the fresh water system can be completely drained by gravity. This basically means that you have every part of the piping sloping towards the low point drains. If you do that, winterizing is very very simple: open the low point drains and the faucets, and wait for the water to finish running out, and then pour a little antifreeze down any drain traps.
A couple of drops of water in a pipe will not cause trouble. A fitting that's at a low point filled with water will likely burst when the water freezes. (PEX piping is elastic enough that it generally is unaffected by freezing water, but the fittings are of different and less pliable materials.)
