First suggestion (since you asked for advice)...

QUIT PLAYING AN ACCOUNT THAT ISN'T YOURS. And I'm one of the more tolerable folks on the boards here. Seriously, if you aren't nailed yet for violating the Terms of Service, you will be, because believe it or not, there are quite a few folks that hate us for one misguided reason or another. Make a trial account in YOUR NAME, pay the $20 for a vanilla WoW account upgrade after the 10 days (although if you use RAF, you'll be to level 20 in about 9 hours with the XP bonus). If you can't afford another account, then this style of play isn't for you. Really, it's not.

The bottleneck is probably your processor, only a 4400 dual core. I had issues with 2 with an 8800 and a 5000+ Black Edition overclocked. If you are using keyclone, set your maxfps and maxbkfps for each client, anything over 30 on the secondary PiP window is overkill in my opinion.

If this is your first set of toons and you're boxing a pair of melee, stop while you're ahead. It's a pain getting them both in melee range, facing the right direction. Mage/mage, warlock/mage, any caster/caster combination would probably net you the results you're looking for. Since you won't be running full groups, then getting a tank/healer isn't necessarily a priority.

Mimicking mouse movements went away a long time ago (search the forums for "MiniMap Ping Targetting" and you see why. It was an exploit. If you just want to mimic the mouse interaction with NPCs, I highly suggest getting the multiboxer friendly addon "JAMBA". Look on the forums here under... Macros and Addons.

Or check the Wiki. Probably the first place to look, read the stickies here, as they answered all your questions after I looked them up. Not hard.

Once again. GET YOUR OWN SECOND ACCOUNT. Seriously. Oh, and have fun.