Not all tetras will work. Some tetras like black skirt tetras are notorious fin nippers. You might want to look up information on the specific species, some have a tendency towards nipping bettas, as the tetras are must faster than the bettas. I have never heard about nippy rasboras, however. You will want to add the school first because they need more time to adjust and settle in, finding hiding places, etc. Shrimp have a very low bioload, so I don't think that would be too much. If you want to find out the filtration capacity for your specific filter go to aqadvisor.com
About the java fern, beware that it cannot be planted directly in the substrate, it needs to be tied to something, I made this mistake and I will have to do some tank rescaping :\
I just did my first community tank too with a school of tetras, there are still things I'm figuring out about keeping a community tank but it's a pretty fun process. I had to do plenty of research, and this site is a great resource. Keep up the cycling, it takes forever, but its worth it.