is wordpress fully customizable? refer me to wp resources plz!

and secondly is customizable a real word? i think i'm getting tired here...

anyways, what i'm tryng to get at is, with the proper knowledge of the wordpress system, cani basically build whatever design i have into wordpress? i have just had my eyes opened to the huge advantage wp has over babelogger when i comes to seo, and its got me thinking that maybe its worthwhile for me to consider learning the wordpress ropes a little more.

at the moment it seems like it will set me back alot, but the more people tell me, the more it seems like in the long run, wordpress might seriously be the way to go...

are there any other wp resources besides wordpress.org that anyone can refer me to...