Are the worms small and white? then most likely they're planaria and they can be a problem for shrimp and small fish(if they're big enough).
I've heard a very small amount of dog dewormer can be used to get rid of them without harm harm to any of the inhabitants(except possibly nerite snails).
You should post a pic of the worm so to make sure or you can search for a photo of a planaria and compare it to the ones in your tank.
flat with an arrowhead definitely sounds like planaria...definitely take a look at the link H20gal posted though to make sure as it does have pics. They aren't anything more than a nuisance (some fish might enjoy them as a snack even) but they can be a sign that you are overfeeding and there is a lot of leftover food. Try cutting back or upping the frequency of water changes/substrate vac'ing and see if that lowers their numbers.
As for the beetle, I have no idea. Any chance you can catch a pic?
