I am pretty sure my valve stem seals are shot. If I idle for about 3-4 minutes, then move somewhere I see a small cloud of smoke. Haven't noticed any during hard shifts or revvin it though. Do I need to change them right away? Obviously its not good to burn oil... but am I killing my engine lets say...if I didn't change them until spring?

 

Oil burning can cause material buildup on your pistons or exhaust valves.
Also, you'll need to clean your spark plugs quite often.
I do believe that letting it run like that for a long time can damage the catalytic converter as well.