Bricks, Masonry, Asphalt and Concrete - Covering a cement slab with fieldstone

Have lots of remodeling ideas but I'm not an expert. My Dad poured concrete slabs for a landing outside back door. I was wondering if they could be covered with mortar and fieldstone? Tired of painting them every year with cement paint and thought the fieldstone would look alot nicer.

fieldstone dresses up concrete very well, you just have to make sure you dont leave any holes for water to get in and pop up the fieldstone, i usually use a thin set type of mortar called superbond, its almost like tile thinset but its ment for bonding to concrete, unpainted of course but if you scrape or grind off the paint it will bond to it if you cant get it off just skim coat the whole surface and let it dry for a couple of days and away you go, make sure your flagstone is all the same size roughly give or take 1/4 inch or so nothing bigger though because you dont want to much morter under it just enough to level it. its is always a good idea to seal it afterwards with a good penetrating masonry water sealer when your done ths will keep the water out.

Now I just have to figure out how much stone I will need. Is it best to lay out the stone before or do as you go. Remember I am a newbie here...

Are there any different types of fieldstone to use over concrete vs a sand set base? Is flagstone basically flagstone or do they "finish" one side of some that are meant to be walked on? (to make it smoother or "flatter") I'm looking at irregular shaped stone (not square or rectangle) to go over a front porch.