If you have the app, these maps can be synced to your various devices, downloaded, and printed for back-up.
We've worked on this for about six years now... founded the company soon after moving to SF and joining Hacker News.
1) What version are you on, the latest iOS version we pushed, 9.1.3?
2) When you say it switches zooms randomly, is this just while looking at the screen, it jumps? Any other info?
3) You can also "Download Map Along Track" too - for any saved route or trail. We never considered polygonal downloads to be that useful, and also adds complexity to the UI. We'd do it, but it's not a priority, and we'd want to do it just right.
4) When the Guide Me line is wrong, in what way? Does it not end on the waypoint? Does it not start with where you are?
Could I get you to dump your idea on UserVoice here: http://help.gaiagps.com/forums/118985-ideas-for-gaia-gps
Then you will get updated if we make progress, or if others comment/vote.
2) No lite/trial version besides the website (but email for a refund anytime). There will probably be a free app along soon though, useful on its own, to help market the paid products.
3) As for Gaia's IAP (GaiaPro), we added that much later, so I would call it "optional."