The holes in your Brug leaves are probably from little green caterpillars. If you can look at it with a flashlight after dark, you'll be able to see them pretty well and just pick them off with your fingers, or a pair of tweezers. If you want to spray something to kill them off, Bt is the stuff. It's sold as a concentrate at any nursery or garden center.
The SuperThrive does have a rooting hormone in it, so might help with your cuttings, but other than that it really doesn't help anything. It's an expensive "magic potion" with a lot of stuff in it that plants can't use, and even the rooting hormone they used to use is banned in something like 18 states. I haven't bought any for years, so maybe they've changed their formulation. I know they had to change their label because it used to make extravagant claims that were widely disproven by research. None of the research I read had anything good to say except it "may help with rooting" and there were even some adverse effects observed by people who sprayed it on their orchids.
Use the MiracleGro at half strength until your brug starts showing strong growth then go to full strength. They are thirsty, heavy feeders.
