The different types of aids (I only know BTE and ITE right off -- behind the ear and in the ear) are usually of different powers. Basically, as in anything, bigger= more power. The behind the ear aids are bigger and more powerful. The ITE's are smaller and less powerful.
I think your loss is right on the cusp, so you could probably get away with an ITE. Definitely check with your audiologist.
Here's more info about implantable aids:
The informal buzz on it is that it's too new of a technology for people to be comfortable with implanting
. There is already new nanotechnology. Anytime you are actually physically going into the ear there is a risk of permanently damaging the ear and losing any residual hearing. What I've seen about this is that it seems promising but too new -- wait a while (5-10 years) and then see.
With your level of loss, I really don't think you'll need anything so drastic. There are a lot of really good, high quality hearing aids out there that can make a big difference for you.
But yes, your audiologist should be able to really recommend the best for you.
I had a behind-the-ear aid, because my hearing fluctuated all over -- I was able to adjust it myself. Sometimes it was more power than I needed, sometimes not enough. (When it was more, I could sit at one end of a long [like 150 feet] hallway in school and hear the whispers of kids at the other end -- but I digress.)