The borax dissolves very quickly. I did mine by adding some acid, then some borax, then more acid, etc. to keep the ph from swinging to far. Walmart didn't have enough borax to do my pool all at once, so I finished up over a few days.
You can broadcast the borax and baking soda. I put it in a measuring cup, break up large clumps with my hands, and scatter it over the surface. If I missed any clumps I usually break them up with the pole brush.
The liquid chemicals I slowly pour around the perimeter holding the cup close to the water surface to avoid backsplash. I always have the pump running when I add chemicals and I also stir them in with the net at the end of the pole.
The only chem I've put in a sock has been CYA because it takes a while to dissolve.
I pour liquids in front of a return jet. The flow from the jet helps them mix in more quickly. Calcium needs to be broadcast across the surface of the pool, but many other powders are easier to pre-dissolve in a bucket and then pour into the skimmer.
It is possible that there is some very very slight damage to the pump seal and some pool heaters if you pour bleach directly into the skimmer but many people do so none the less and have not observed any obvious problems. I prefer to pour bleach slowly in front of a return while the pump is running.