[vulgarshudder]

Yes there are kanji that are used for names only, with no meaning.

If you have problems with Katakana and Hirigana you'd best give up the whole japanese learning now, cos it's not gonna get easier after that.

Hardest part is kanji. Trying to learn them is like trying to fill a sieve with water for me, it needs alot of topping up constantly. ie i'm liable to forget the reading or how to write kanji I've not come across for a while.
I can guess the meaning of kanji if I'm in a pinch.

Grammer...I never found so difficult, but I learn easier through understanding something rather than rote memorising, hence kanji woes. Transitive and intransitive verbs I've made some embaressing mistakes with.

Keigo was drilled hard into me, depends on how used I am with using it at a given time. My old ojyosama uni everyone used redicious levels of keigo that always is good for a joke now days.

But yeah, kanji.