"Desu" is a copula, but
it's also used as a way to jack up the politeness of sentences, typically with an i-adjective.
Let's work with a simple sentence: I am tall.
If I'm saying it politely (i.e., not amongst friends I'm super-casual with,) I would structure it rigidly with all parts of speech and the more formal version of the feminine "I' - Watakushi wa takai desu.
To make this negative, we change not the desu at the end (normally, we would change desu to ja'arimasen), but the adjective takai - Watakushi wa takakunai desu.
If I were hanging out with only my friends, not worried about offending anyone, then I could (assuming I've established myself as the subject already) drop a whole bunch of sentence parts and basically end up with: Takakunai.
And then, if I want it to sound soft and feminine, add a 'wa' sound to it. Or if I'm searching for agreement, like "I'm not tall, am I?" I'd add a yone or a wane to the end. Or if I want a "I wonder if I'm not tall?" feeling, I'd use kashira at the end. But those are because I'm female. Guys would use different sentence enders or the neutral ones...as male sentence enders are mostly casual or kind of rude.
As for the super-kawaii talking you hear for girls (mostly in anime), no...real people don't usually talk like that. It's a thing in Japan. They LOVE cute things, so they over-cute-ify EVERYTHING. Real women can't even compete.
Kanji wa...Well, as for kanji, it's actually a LOT simpler than you'd think, if you go about it the right way. Instead of looking at it from a stroke order perspective, learn the radicals with mnemonics. Like I said, I started in late January, and I already know this many kanji at varying levels of memorization (The colored ones. This is a standardized list of kanji someone decided everyone need to know):
After only a few months, I am beginning to understand low-level manga...and the system gives me the tools to look up things that I haven't already learned, too.
For those that are willing to shell out the money, it's $80 a year for a subscription at http://www.WaniKani.com
($50 a year if you're a member of http://www.Textfugu.com
You can do the first two levels free. Lower levels are slower to start, but it builds an important foundation, and if you take it slow and make sure you get everything right, you can level up every 8 days.
The first step, really, though, is to learn hiragana. Seriously, being daunted by hiragana was what kept me from really learning Japanese for TEN YEARS. And when I knuckled down, I learned all of it in only two days.