Lip augmentation can be done by variety of methods from injectable fillers to implants. Mouth widening will require an open commissuroplasty which can open up each side by about 5mms.
Please understand that asymmetry in facial features is normal and there are studies that suggest a little asymmetry is actually desirable and makes your face more interesting. However, a tiny bit of Beletero to the smaller side would make this more symmetrical.
This type of "trap door deformity" of scar is tricky to deal with. It requires a combination of very small precise manuevers, occassionally staged, and some good karma afterwards to get significant improvement. Having said that, I think it would be worth doing with an experienced surgeon.
