1-BCWP and BCWS rows are not showing anything though. (although I also have a baseline). i checked both the current start and finish dates interval and the basleine start and finish dates interval but no BCWS and BCWP is visible. Why?

What is your status date? BCWP and BCWS are dependent upon the status date. Are the tasks scheduled before the status date?

2-lets say I wanted to know the EV for last month, July. If it showed BCWP, I would simply add the values of BCWP for the interval of July 1- July 31 right?

No - it is not necessarily additive. BCWP is based upon % complete (or Physical % complete) * time phased baseline cost.

3-BCWP would add up to fixed cost and would show between current start and finish dates of that activity correct?
No - see above.

4-BCWS would also add up to fixed cost but it would show between basline start and finish of that activity correct?
As of the status date.