You can't name the chapters in Emby itself, but you can use MKVToolnix to name the chapters and Emby will use those chapter names.
Look up the disc on DVD Compare, which will have the runtime for each extra. Easy to then pick out what you want. If it's not listed on there you still don't need a standalone player, you can use MakeMKV's VLC integration to play the disc in VLC while you have it open in MakeMKV, and again once you have runtimes it's easy to pick out what you want.