I am 5'10 and 145lbs , which since would you recommend for me?

I am 5'10" and 140lbs .... Small fits well - I also wear a small in Russel and a size small in Champion .... wear well on me even after wash and dry .....

Are these pants light weight for summer wear?

The weight of the pants are between traditional sweat pants and thin shiny jersey sports wear. I bought them for a friend on dialysis. He needs to wear pants because it is cold in there but may sit outside in the heat waiting for the bus. He just started wearing them and seems to be comfortable in them with the blistering heat we have been having in California.

inseams are not precisely made and in this instance varies . Left leg 32 inches right leg 32.125.I would say the goal was probably 32.5 as their has been shrinkage after 2 washings at normal temperatures.