Thanks for the response! I’ll do my best answer your questions.
The sump stand paint wasn’t anything water proof. It was just the canned spray paint. The display stand was shot with the same canned paint. If your display stand is to house your sump, you may look for a water proof paint to seal it.
The electrical work down stairs was done after the joists were doubled.
If you were to double them with electrical wire already there, you would need to disconnect the wiring and remove it to add joists. I highly suggest having a electrician do this work for you if you don’t have any residential electrical background. I’m not a licensed electrician, but I’ve done quite a bit of this kind of work in the past and understand fully what I’m doing safety wise and as what is required to do the work to standards and codes.