Guild Hall skill trainer

I'm wondering how the skill trainer in the guild hall works as in, what selection of skills are available and how are they purchased?

Is it that only skills I have unlocked are available there?

Core skills only.

Don't waste your money unless you want convenient cap sigs. In other words, he's useless.

http://www.guildwarsguru.com/forum/s...php?t=10264391

There was a thread with almost the exact same title only 4 threads below this one. Reading it would tell you everything you needed to know.

Only core skills you have unlocked.