CalMag - If using RO or distilled water or very low ppm tap water, yes you will need this, get a bottle and start giving 3ml/gal with every watering. If using tap water with lots of calcium, you won’t need it.
DE - used to help eradicate bugs that walk around on top of your soil, it cuts them up as they move thru it.
Molasses - I don’t use it, read all about it here Black strap molasses during flower. Your thoughts on it? - #4 by Majiktoker
Sledgehammer - If using Fox Farm nutes, might as well use Sledgehammer. No need to flush if you’ve been using ocean forest and using no nutes at weeks 4 or 7. In Happy Frog, should start nutes at 3rd week, good time to start is after the transplant out of the solo cups or right before. 1/4 to 1/2 dose of feeding schedule. Won’t need to flush at week 4 because you should have just recently transplanted so the first flush you really should do is at week 7 after feeding them for 4 weeks, which is right before transplant to the final pot time,
Lab testing - not being legal in my state, no clue, there are labs on the web that you can send a sample to and they’ll tell you the thc and other stuff for $50 - $65 a sample.
TDS meter - every grower should have one, useful for testing water quality by telling you the amount of dissolved solids in your water/nute mix, can tell you how strong your nute mix is in ppm and EC. Can also be used to see how much nutes is in your soil by testing the runoff with it.
Super Thrive - waste of time snake oil IMO, just use quality ferts, there is no magic there. Have not used in 20 years.
Bembe - Fox Farm molasses replacement product - feeds the microbes in your soil
Cha Ching - Fox Farm add-on product to get more of your money, to enhance late flowering production, never used it.