I always go off topic, usually I'm good at coming back around though
I cannot believe 12% tax, here in California it went up to 8.75% I think, it had been 8.25% and is up to something...many reasons I miss Oregon, I enjoyed paying $19.99 on the dot.
Yes, I'd definitely move the betta back to the 5g, I wouldn't keep one in any less than 10g mine is in my 36g. As for a 2.5 I think shrimp are fun, most around here know that I'm a die hard shrimp fan whether it's cherry shrimp, crystal, bamboo, bee, amano, etc. etc. (except the bamboo would not go in a 2.5g nor a 5g) but I think a real planted shrimp tank would be fabulous. Maybe with a nerite, might have to supply the nerite eventually with algae wafers I imagine it could run low on food.