You can keep ADF
's with other similar sized fish without issue (just keep them fed), however I tried keeping ADF
's and some Rasbora's in a 10 gallon once and felt that it was too crowded and both were stressing each other out, since neither had any place to really be away from the other for a while. I'm sure someone else has had it work though so your mileage may vary.
After seeing how ADF
's behave I would be hesitant to keep them with shrimp, they're kinda dopey when it comes to feeding, often lunging at food and missing entirely or biting each other by mistake. So I could see them chomping on some shrimp by mistake, and wouldn't even be surprised if they just saw them as prey.
Betta's being kept with other fish and shrimp usually really depends on the temperament of your betta fish. I've had betta's that would not tolerate being near any other fish/shrimp and attack them and I now have a betta fish that lets Kuhli loaches lay on top of him and isn't aggressive towards anything.
Just be sure that any fish you decide to possibly keep with them isn't a fish known to nip at fins/be too boisterous as they will stress out the Betta.