LST is probably best, because you don't get to choose teh vege time. Shoot for 4-6 primary colas and let it go vertically. De-congest problem areas but otherwise do your best not to prune the plant any moer than necessary.
Overwatered? Let's just go over a basic SOP to follow.
1) always water entire substrate. Never choose the volume of water... you simply give what it takes to get the entire thing wet. A little runoff is fine in soil -- not sure what light-mix is techinically.. it has organic amendments, so to avoid wasting those i'd treat it like soil. In a soilless medium you want a religious 10% runoff. the runoff maintains a consistent equilibrium around the roots -- if using "hydro" nutes, this is how you should treat it.
2) wait for top layer to dry -- depending on the water capacity this may be when it first starts changing color (if mostly coco this may be the case), or with a medium that holds more water per volume you'll wait until top 1" dries. Once your context matches, you go back to step 1.
Easy-peasy. Don't over think it. Watering is not rocket science. It does not need to be some esoteric, highly sophisticated process. Water until it's fully wet, wait for it to dry and repeat.
how often you add fertilizer depends on the concentration you are using (for "soil" fertilizer). this will be added every other or every third depending... over time it averages out to a similar amount given, not by coincidence. with a hydro/soilless context you add a fairly low concentration each and every irrigation.
if you deviate from this, adjust. Don't make it complicated. in flower you can irrigate slightly sooner and make use of a robust root system that results from a plant that has to seek out water a bit early on.