You probably are using and keyboard or keyboard encoder and have the buttons held down. Notice what happens in notepad when you hold a key down.
If you turn the key repeat off for that particular keyboard it should fix it. It's entirely possible there might be a delay though if you have a system with lower resources or a lot of things are running in the background. I'm sending the keys via direct memory writes afterall.
I'm using cheat engine. I search for memory addresses as the game is running and any code I look through is pure assembly via cheat engine's interpreter. In all honesty though the game is butt simple, so looking through code isn't particularly necessary to alter things.
You would have to take a snapshot for me to tell what is going on, but the answer is no, there aren't any resolution limitations (although just by the way the game is made, it does seem to have trouble with really low resolutions).
Yes I never found the 1up counter, but honestly I'm on other projects atm. If you want to look for it knock yourself out though.... I'm just not sure when I'll get around to implementing it.
Again feel free, but you might want to make it clear that I'm not a member of the hyperspin forums, I don't visit them and if someone asks me for help over there they are essentially talking to themselves.