Types of ringtones for 6101?

I'm a complete newb at this, so please bare with me. T-Mobile has the Nokia 6101 for free and I'm interested in getting it, and one of the main things I'm interested in are ringtones. I've seen many different names.. True, Real, Master, MP3, but they all seem the same. Poly, and those. Is there a difference? One ringtone website offers "True" type, but on their compatibility chart, NO phones accept "True" type, just Poly and "Master".

Basically my question breaks into three parts; 1. what types of ringtones are accepted, 2. are MP3, True, Master etc. all the same and 3. since I have read that this model has PC connection and supports MP3 ringtones, can I create my own?

Thanks

With the 6101 there is a recording option which lets your use your recordings as your ringtones. So what you can do is, hold your phone up to the computer speaker, play the song you want and then record the part of the song your would like as ringtone. I have tried this myself, and some sound pretty good, but some don't.