Sweet, another aveo!
I'm creeping up on you with my last tank, and after I get my maintenance taken care of my numbers should improve even more. I'm glad I'm not one of the only aveo drivers on here
I have a certified mechanic friend, I'll ask him about the shifting. He also has other mechanic friends so I'll get their opinions on it as well. I know for a fact that they do transmission work.
Good luck to you and I hope your mod ideas work out in the future. I'm planning a few myself but can't do anything to it till I do the timing belt, hub bearings, valve cover etc.
Oh and btw, I do EOC in mine and it seems to be fine. Don't know if you have the same year, but any 2004-2006 should be the same. As long as you're careful to have the car in neutral, you can EOC safely. You'll still have a few good pumps on the brakes left, and the steering doesn't get difficult until under 25 mph. Of course if you don't feel safe doing it, don't do it, but it is possible.