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It should be fine. If the Betta seems to be thrown around by the filter current, you can try to block it. I tied a strip of pantyhose material around the filter so it would block the current a bit.
The intake won't be any problem at all.
And the ghosts should be just fine, they have a higher chance of surviving than some other types of shrimp. But the loaches I'm not sure about. I think they need a bigger tank.