It's an 8 gal. So far we have a hitchhiker snail in there who snuck in with the plants.
Just a note, if it is a pond snail it will eat your plants, so you probably want to get it out of your tank before you have more of them appearing. If it is a Columbian Ramshorn, same thing--it will eat your plants. If it is a Malaysian Trumpet Snail (MTS), your plants will be safe. And if it is a European Ramshorn, your plants will be safe. Apple snails you hear various reports about, but they are known to eat plants at least sometimes so I would consider them a risk in a planted tank.
The fish store here is a little limited on stock but over the weekend I may be able to get to a larger one about an hour and a half away- would fish be able to stay in the bags for that long? what about a very small plastic tank?
Yes, they should be okay for that distance in their bags. It might be worth asking the pet store if they can fill the bag with pure oxygen rather than just air (some of the better aquarium shops can do that; most chain pet stores can't). You might consider bringing a small cooler with you and putting the bag(s) in that to help insulate them and maintain their temperature during the trip home. If you don't have a cooler, a cardboard box lined with a towel will serve much the same purpose. Either way, ideally you want to keep the fish in darkness during the trip, as they are subjected to less stress when being moved in the dark rather than in daylight.
I would strongly suggest NOT putting the shrimp in with the betta. I tried it with my male and female bettas and they ate them in no time flat! I have three cories with my male betta, but they are in a 10g, I would think putting that combo in an 8g would be pushing it a bit.
This is a perfect example of how individual betta personalities can be. The last two weeks I've kept a female betta with 3 ghost shrimp in a 2.5 gallon tank without any shrimp losses. For the first 24 hours the betta seemed a bit bemused by the shrimp, and there were several times I thought she was about to attack but...she never did, and now it's clear she views the shrimp as neighbors rather than lunch. I have recently moved all of them into a 10 gal and she still noses around and "bumps" them with her snout from time to time but I think that's more playful than anything else. So you never know; shrimps might work or they might not. You can always try with a few ghost shrimp (many pet stores sell them as feeders at a price of like 6 for $1), that way if they do get eaten it's not as big a loss as if you pay several dollars each for Red Cherrys and your bettas make a meal out of them.
P.S. -- Some pics to help you ID snails and such if you aren't familiar with them:
Plant-Eating Snails
Pond Snail (size typically 1/4" or smaller)
Columbian Ramshorn (color can sometimes vary; can get up to 2")
(also called Giant Ramshorn)
Apple Snails (coloring can vary; size up to tennis ball sized!)
(also called Mystery Snails)
Plant-Safe Snails
MTS (size up to 1/2" or so, maybe 1" for really really big ones)
European Ramshorn (comes in many colors, but mainly brown; size up to 1" or so)
