Q - Does OpenAL support al cards ?
A - Yes most of them
Q - Do i have to distribute some library(es) ?
A - Probably not included in windows
Q - Is this the only 3D audio API available on multiple platforms ?
A - Seem it is the only 3D audio API crossplatform
Q - Any dependencies or other strange things i need to know ?
A - No, it seems to be able to use whatever support it finds

Thanx anyway guys, maybe someone else will find this useful.