AC SWITCH IN CAR WILL BARELY TURN

No. This is posted in ac cars and trucks...in that case either the blower motor or the blower motor resistor is bad. If a home unit then either motor or run capacitor are at fault UNLESS you have a multiple speed fan in which case the speed control board may be bad.

Could be a leak in air-conditioning line or compressor on its way out does it squeal at all

You didn't post what year it is but it sounds like the blower motor resistor may be faulty or bruned out . depending on year could be the switch

May be a restriction in the air intake of the HVAC unit or a door/flap closing for some reason not desired .

Try replacing your cooling fans since both fans are probably not coming on at the time the a/c is on. If your car uses a single fan, then it must have a hi and lo speed so probably the low works but the high doesn't. If you can barely hear the fan spin then it is probably working in the low speed position and you should check that.

any low fan relay or just fan comes on when the aircon switch is on

The window go up slowly as the power of the power window is being low ie it needs now some repairing ie meintanance. So as the switch, in this case just install the new switch (confirm with mechanic.)
Yes you can make the a/c on but check out that it does not make any flactuation in battery. For making car faster just tune up the combition chamber of your car.

defective ac compressor,that would be my guess

Replace the ignition switch.

Your car has a IAC IDLE AIR CONTROL MOTOR , this is on the throttle body and its job is when you turn the A/C on it adjust the engines rpms to make sure the car doesnt stall . It is located on the throttlebody and is a cheap part. As far as your wipers you have a multifunction switch witch controls the wipers and wiper speed. A common part to go bad. The wiper motor just recieves signal from the switch . Also check to see at the part store if you have a wiper control modual or relay as well.