Hiragana and Katakana have no difference in levels of formality. Hiragana is more like the "default", while katakana is used for special cases like creating italics or emphasis, spelling out foreign words, etc. You'll see both of them quite often.

You do not need to "learn" romaji; obviously you are quite competent with the roman alphabet. Perhaps learning a bit more about what hiragana and katakana actually are would help clear up your confusion, but really, all you have to do is start memorizing which kana corresponds to which syllable.

For no good reason :)

Go ahead and learn kana first, then start working through RtK for the kanji.

I learned Hiragana first.
Because the system I was using sometime wrote using it,
so I had to know the hiragana to know what the word was.

Learning together is the best way.

It depends on what is going to me most useful to you. I'm mostly interested in communicating through the internet, and don't plan on going to Japan for quite a few years. So reading and writing matters most to me. I am working on my listening and speaking because I don't want to get hit with it all at once, but most of my dedicated study time is reading and writing.

Hiragana is the basic kana, what you'll see most often. Katakana is used for foreign-based words and sound words. As for kanji, they're used whenever they work, if that makes sense. Or rather, the kana are used when there's not a kanji that works.

It sounds like you've poured a good bit of money into materials already. You may regret that. It's really better to start with a minimum, and then buy more as you need it. Not only will you waste less money, but you're more likely to use your materials if you attain them out of need, rather than, "Oh, this looks good."

First speak because writing and reading go hand in hand. SO you learn one and you learn the other.

Write. If you study writing first, then you'll know how to read it, when you learn hw to read it, you'll know how to say it.

Could you please explain a little more about what you mean by "sound" words... or better yet go a little more in detail about the differences between the two (Hirigana and Katakana). Metaphors are the greatest!:D

Also, what is the the best all around book any of you can recommend on writing kana and kanji?

My problem with AJATT is that his main point now is the sentences - and unless he writes down his sentences, no beginner can really use that method.

He does have a couple of good points - use a SRT, study often, and have fun - but everyone knows that already.

yeah, i COMPLETELY agree with writing/reading first. i tried speaking first, i'm completely FAILING D:

maybe take a class instead? there's a class that's 2 weeks long in the nearby community college where i live, but my friend says there r tests everyday .3. gonna try it this summer.
u could try something like that. my friend took the class and now she can write/speak/listen to everything. the only thing missing is Kanji, which u can learn online if u want -shrug-

Onomatopoeias. Woof, chirp, ding, etc. There's really not much more difference. You'll be safe using hirigana when you aren't sure, but keep in mind that if it's a loan-word (naifu for knife, Amerika for America, etc.), it'll almost always be in katakana.

I bought two books on kanji. One was for the first hundred, and the other is a dictionary. I only use the dictionary. For kanji, I just use various online sources and flashcards that I made for myself. For kana, I pretty much did the same thing. Look up the charts on Wikipedia or something, and study about five at a time. You may learn differently, but for me, it's all about constant repetition for all the characters. I only use books for grammar.