If I would make a good game title with gamestudio I would not hide that it was done with it, because I think GS has a lot of capabilities. I could not imagine that they would not try out your game (thats what you wanted), only because it was made with GS, maybe they would not do it, because the first icon is still a standard one(unprofessional).
So I think that other points are not really needed and I would really like to see an in-build option for an icon.

btw: what I noticed was, that I could not use an icon with an alpha-channel (just visible or not) and that I couldn't use an icon, that uses different sizes in it. I would appreciate if you could also implement that