Welcome to the forums, and to Vitz Owners' Club.
I got my Vitz 2004 work done from AutoClub (I-10/3). However, going there is of no use if an inexperienced mechanic is handling your ride there. They have a couple of good one, but they are not always available. So, I'd better leave it to experts here to reccommend a good workshop.
For things to get changed, it is reccommended that you should change ALL the fluids if you are not sure when they are last changed. Check the brake leathers also.
Assuming that your Vitz is on CNG, i think, you should get its tuning done and you might feel better. However, yes, auto tranny will always be less powerful than manual one with the same engine capacity.