Bad quality scissors will invariably suck for lefties because the grip of a left hand pushes the blades apart, vs. with a right it pulls them together. Scissors are my #1 gripe as a leftie too.

I use the mouse with my right because the rest of my family is right-handed so it was on the right and I just learnt by copying. I don't mind it, as I can type fairly reasonably one-handed with my left hand - much better than I could with my right - so it means I can still do short typing bursts one-handed without lifting my right hand off the mouse. When I type with two hands, I find my left covers about 60-70% of the keyboard vs. my right doing about 30-40% of the keyboard.