Cost of cutting trees and removing rocks from a lot

[Kaustubh Johri]

I am looking at 2 lots in Atlanta suburbs - 0.5 Acre each. 

First lot has a lot of trees. I wanted to know what would be the cost of cutting trees (ballpark figure). Is there anything else I need to be aware of after cutting the trees down ? 

Second lot does not have any trees but has a lot of rocks (as big 7-8 Ft long). Is there any thumb of rule to excavate dirt and rocks ? This will help me in estimating my development cost. 

Thanks !