Yes, it is vital! Keep going, I promise it gets easier.　がんばる！ Kanji is tough, yes, but everything will smooth itself out if you keep trying. ^^

If I were you, I'd wait to learn the kanji after you'd mastered the kana. It's up to you, but yes, if you're going for fluency, Kanji is 100% necessary.

I also am studying japanese. I have learned both hiragana and katakana and am learning kanji as i go along learning vocabulary. I feel it is very important to learn kanji but i would wait until you have a steady grasp on at least hiragana. Learning hiragana and kanji at the same time is possible, i did so for a very small time, but was very difficult for me. No matter what you decide however if you intend to read japanese as well as speak it you will need kanji and my japanese teacher always said the sooner you start the better. Good luck!

Depends on how far you want to go. Not absolutely necessary for casual sight-seeing, but necessary for business or living. Several hundred kanji is enough, though.

hiragana is very easy, nothing "increadible" in it... and yes, you'll need to memorize about 2 thousand kanji