My central corneal thickness is 450. and I have number of -10 in right and -8 in left eye.

Yes, you may wear contact lenses after PRK surgery. Alternatively, you may consider a laser refinement procedure to improve your outcome. 

Moderate activity is fine. I would avoid swimming for 7-10 days to allow your corneal surface to heal and thus make infection less likely. 

In general most refractive surgeons will do both eyes the same day. This is perfectly safe and makes the recovery of visual function quicker. 

Be patient, it is not unusual to have an initial overcorrection with a high prescription.  It may regress over the next couple of months.  We generally wait 6-12 months before deciding on an enhancement to insure a stable prescription.

It is most common that one eye heals faster than the other in PRK.  It is unusual for them to both heal at exactly the same pace.  The frequent use of artificial tears will speed up the healing process and it is important to avoid rubbing of th eyes which can cause the new surface...

It is impossible to be both nearsighted and farsighted in the same eye. It is like a number being both positive and negative at once. More likely, you were nearsighted with presbyopia. Many people confuse presbyopia with farsightedness. Presbyopia is the aging of the lens inside the eye...