Absolutely you can. The following will hide a button if you mouseover it.
1. Give the button a ControlID of your choosing. I'll use 'blah' (don't use quotes in the Designer)
2. Add an Custom Event to the button. Choose mouseover as the event, then use the following JS:
var mybutton = document.getElementById('blah');
mybutton.style.display = 'none';
Note you probably want to add a onmouseout function (or some other function) to reshow the button... JS is similar to the above but just set style.display = '';
Changing textcolor is very similar to the above. You'd just use style.color = '#abcdef', where abcdef is the hex value for the color (use google to track down the value for the color you need)
The main thing that's important is to provide ControlIDs for whatever control you want to manipulate... because we need to track it down with JS getElementById