1. if its a ball mouse take out the ball and wash it, scrape the rollers with a pin etc to remove the gunk. if its an optical mouse and cordless change the batteries maybe.
2. as above. also check your control panel/mouse/motion settings or similar and adjust acceleration and speed here to your liking.
3. important thing is to install something and keep it up to date. i use AVG antivirus and zonealarm firewall (both free) and they do a great job with little messing about setting up so would recommend them. do not run any more than one av and one firewall at a time though. norton products are good also.
i would also re install adaware and spybot again, keep these up to date as well and also grab a copy of spywareblaster click here as this will stop any spyware even getting on to your system in the first place. spybot recommends you use this also.
for a great safe to use clean up tool click here use the default settings