How can you pronounce the l in calm and palm?!?

You mean physically or morally? It's a dark l (aka velarized alveolar lateral approximant, link) for sure.

And you all are aware that not everybody in the world pronounces English the same, right? For more information see the delightful IPA chart for the various, major regional forms of English and how they differ in pronunciation (link).

Oh, and I do not pronounce the t in often either.

Ceci n'est pas un seing.