sndk1999

I have a 4 cyclinders accord with automatic transmission. 120 K on the car.
here are problems
1. The A/C is weak and leak I have to re-charge it every year
2. When I turn A/C on the engin noise is louder when accelerate, when I turn it off the louder noise will back to the normal level.
3. when idle/cold the engin moise is louder
4. gas milage is not so good 23-25 mpg on high way

The car was serviced by Honda around 90-99K with change timing belt cv joint et al

turn up was done month ago except gas filter, transmission fluid and cooling fluid was not change ( will do it in few weeks)

my questions is
1. Do I need to adjust valve clearance? how much it usually cost?
2. Is the A/C cause the louder noise when I turn it on?

thanks