There was an upgrade to Firefox last week. I haven't had any problems on Windows 7, but it could be contributing to your issues. There's a setting In Firefox to have you notified before updates are installed. Tools --> Options --> Advanced (left sidebar) --> Update (tab at top of screen below URL) --> Firefox Updates: --> Check for updates, but let me choose whether to install them (Radio button to check).
I switched to this option a couple of years ago after having problems with Firefox installations on an even older version of Windows. Using your favorite search engine you can check to see if there are problems with the installation reported before upgrading. Firefox sends reminders multiple times, unless you request it not to, so not upgrading when the popup first appears (and sometimes disappears before I can read it) has not been an issue.
I gave up on IE several years ago when it kept loading a different homepage than what I had specified, and loaded slower than Firefox. Also I was using apps not available on IE.
I have a wireless keyboard and have the same issues with typing faster than it can handle, so I'm not sure the wireless keyboard will help.
