I would recommend a few months of retin-A instead. Use it once every 4 days to start with until your skin gets used to it, then you can use it more.
TCA is quite a deep peel.
Fraxel or other fractional laser treatment will help scars and some kinds of pigmentation but not post-inflammatory hyperpigmentation
Doesn't really matter if you do it before or after surgery but TCA does require some time to heal, during which you need to stay well away from the sun and your skin will look a bit of a mess. So if you're going to take the plunge I would do it at the same time as your surgery as you will be in hiding after that anyway!