after so much time of being frustrated w/ not being able to use linux and learn linux ppp connectivity because of winmodems, i'd like to buy a modem that will work w/ *nix. couple of questions.

1. are there "standards" for *nix modems? protocols i need? what kind of logos (not manufacturers, but standards logos) should i look for

2. do*nix externals modems connect to com ports or are they made for USB these days?

3. are *nix internal modems bigger (in size) and do they heat up

thank you for your time and any actual suggestion appriciated.