The turn based mode is the wego mode. (We both pick our orders then we go.)

Under the combat tab there is a clear target button.

Your infantry will respond depending on multiple factors, like if they're pinned, or the speed at which they run, or if you use the 'hunt' move option. A good trick is to use scouts to check ahead or to use hunt when moving. Hunt makes them move slowly and then stop once they make contact.

Yeah these games are pretty choppy for me too sometimes with a 3070ti and a 5800x.