1) The Trainer script is written with Stealth 4.x, back then we had so called pseudo-UI (TSTFORM, TSTButton, TSTListbox) but that was not thread safe and due the work on api, we removed that stuff and leave ui things to native languanges.
2) You could check some posts on this forum (in stealth section) about gumps, i prolly explained all useful things already.
3) Yes that happens to me rarely as well...maybe 1 of 200 times i have issues. Other people have more or less issues about the graphical client, hard to resolve when not really repeative.