with no other fish, they will likely be fine, as long as you dont have a filter intake they can get sucked into. co-op fry food should be fine for them.
relax, take a breath. give the fish, and yourself a little time to calm down. if the rasbora got a physical injury from being stuck, there is little you can do other than wait to see what happens.
java ferns will get brown spots on them, it does not mean they are dying. anubias, and java ferns are fairly low care items. a little light, and some nutrients in the water, and they tend to do ok. they do grow slow though.
the prime is likely giving you your readings of ammonia. if it were me, id just back off a bit on the water changes. say give it a few more days in between , and see how it settles in.