Spring RTS Engine

What is autosmooth and should i be using it on my models?

No.

14. Auto-Smooth = Set Edges hard or soft depending on the angle between faces. The angle setting can be adjusted

so that is a yes

My mistake, I thought it referred to automatically smoothing a model.

Make sure to smoth your model repeatedly.

Also, Is Weld important?

clean up is important, manually finding and fixing what ever clean up misses is important

weld can be used to "weld" to objects to each other if they have three or more common vertices (as in exactly overlapping vertices). the latter can be achieved by a loop cut or snapping vertices into position, but the bridge tool almost does the same thing and cleaning up the few extra faces it creates takes less time.