Regarding the finishing that is not correct . All you have to do is tick the box "Leave for Finish" and tell it how much you want to leave on and if you want to also leave for finish on the bottom .
I think your frustrations are pretty normal when you change software as you get use to using software and it becomes second nature. I change to Mac a couple of years ago and I hated it but now there is no chance I would go back to windows , It is just a matter of doing things a different way. There will be quirks and things you will wish you had from Gibbs and there will be things that Onecnc excels at just give it a bit of time
Regarding your post this is one thing OneCNC does right just ring support and it is all part of the deal there is no extra cost. I would also suggest you join the OneCnc forum if you haven't yet . They are the great bunch of people and
you will find you get support 24/7