uh.. wots a maiar ???/

[burrahobbit]

So, is my friend Tulkas a former ëalar, that became a Valar when he came fight against Melkor.

No. Tulkas is a current member of the ëalar. The Ainur are a subgroup of the ëalar, and perhaps the only subgroup.

REAL WORLD EXAMPLE: I am a member of the group called Homo. I am also a member of a subgroup of homo called sapiens. Right now sapiens is the only subgroup of Homo.

Back to Tolkien. Valar and Ainur are two of the groups of Ainur that entered Ëa. Valar and Maiar, are more like job descriptions than anything else. Valar and Maiar are still members of the Ainur (and the ëalar), just as CEOs and secretaries are both still members of Homo sapiens.