Best of luck to you.
Looks like great work so far! Sorry about your losses.
I'd love me some sexy shrimp. I still may get some. I'd imagine that with diligent research, you could find a rock-loving fish or two that could live in there.
I appreciate your attachment to the perfectly fitting plastic top, but that's really what I would let go of. It's not great for air exchange. It's also a heat trap during the summer. It can affect all sorts of things I barely understand... ph, O2, light intensity and spectrum... who knows what else.
Do you want a nano-nano reef or do you aspire for a 20 or 40g system? Whatever your preference, most of your costs will be on testing. A lot of the equipment will suit any of those sizes. Maybe a salt cost of an extra $12 a month for the 40g option. Whichever you prefer, I'd do it now so I'm only buying stuff once!
Go get em!