Mars being the fourth planet away from the Sun really should be able so sustain some sort of life, do you agree?
I do, haven't they found water under the surface though?
They have found that it does have a fairly thin atmosphere, and features consistant with crater impact. I don't know if they found water however.
I wonder how hot it gets on mars.
I dont think it gets much hotter then earth if at all. The rotational and seasonal cycles are nearly identicaly to Earths, as well as the axis tilt that causes them.
But it has no clouds or anything to protect it for the UV rays?
It does have weathering to the surface but I dont think it is caused by atmospheric conditions. There are ongoing invesigations about the past habitability of Mars so the UV is not a problem I dont think. 
Well maybe Tesla will help us get there one day.