Tenshi and firebelly/: the bugs you just reported are not actually bugs, as far as i know, if Construct 2 works exactly like any programming language (don't wan to get you bored reading long explanations here).
Tenshi: if you put a single keyboard event ("On X press") and two separately sub-events ("FireMode = 0" and "FireMode = 1") in an "Else" event type, i imagine it should work properly. Try it!
firebelly: try to use another variable (lets's gently call it "AlmostTrashVar") just to set the number you've inputed directly in the "CurrentlySelected", and then, outside the event "On Up Arrow pressed", set the "CurrrentlySelected" the value stored in the "AlmostTrashVar".
I hope i could help you.
Sorry sir Moderator if I wasn't able to post an answer here. Oops!