New clutch?

I'm pretty sure my clutch is ready to go...It's starting to slip alot under hard acceleration. Also seems like it doesn't have time to disengage because on occasion when I switch to 3rd it grinds. Not even sure if it could be the tranny. When the car is at idle for a while it start to whistle very quietly almost sounds like crickets but as soon as I even touch the clutch it stops....Any suggestions on what it could be or on a good clutch I can put in. Forgive my stupidity, I'm new to all of this.