I’m pretty sure the yellow line means premiere is very sure it can play it back in real time, therefore rendering it to a file is unnecessary. As to your second question i’m sure that would speed things up but you might take a hit in quality.
Thanks for the tip it worked :D, is there a way to set the properties of a track so that when items are dropped on it their y coordinate is not centered but in the lower third? If not i’ll just use the paste attributes.