For safety, I'd add OSB or ply under the tank(s). If the stand was made for tenners, I wouldn't be concerned, however I can just see someone accidentally bumping the tank and a corner flipping into the hole.
Beren, have you checked out Han's Site? It's run by Han (H4N), a member here, and he has some nice plants to get you started in aquascaping if desired.
I've not seen fungus from fresh picked, but then again they were in transit 3 days before getting to me.
I *did* learn NOT to leave fresh picked in a sandwich bag, or they will become moldy and unusable.
The challenge is that microS and TDS don't really correlate well. For microS it depends on temperature and what materials are in the water to conduct. Some people just multiply mS x .7 to get TDS, but that doesn't work all the time depending on the materials in the powder.
If you are offering samples for .50 ea, you could try it yourself since you have to open a container anyway.
I noticed with the shrimp rocks it said it can be used to add gh. Do you wait until the gh hits where you want and take them out, or do you keep them in and the gh is stable?
I have to say, accidental or not, I really like what Monty did with these shrimp. Not everyone would have spent time on them, yet he saw a coloration he liked and decided to go for it. Selective breeding at it's best. Great job, Monty!