The first phase (aside from the preparations beforehand) is probably the most crucial of the bunch - learning the Kanji. It's not because it will teach you the most about Japanese, but because so much in Japanese revolves around it. However, in this phase learning the Kanji mainly means knowing what each represents by its English keyword (though this will change later). Pronunciation, or "readings" are not vital until phase 3.
Yes, there are over 2,000 Kanji. Do you need to know them all? Eventually, yes. There's no getting around it, just through it. RTK (Remembering the Kanji) helps immensely with this, so use it. I'll be writing more detailed articles about using RTK in the future.
Why is Kanji so fundamental to Japanese?
If nothing else, knowing the Kanji gives you an edge when you get to sentences. Even if you don't know them all, there's a good chance you can pick up on the general idea if you know 75% (or better yet, all) of the kanji in a sentence. For instance, if you've parked in a parking garage that closes at 6pm, knowing the kanji for "pm" 午後 as opposed to the kanji for "am" 午前 might keep you from losing your car for the night. Also, knowing the kanji is invaluable for learning sentences down the road because in order to really know them, you should be able to read, write and say them properly. A knowledge of stroke order is invaluable here, and will help immensely down the road.
How on Earth do you set up to memorize over 2,000 symbols?
SRS. SRS. SRS. Did I mention SRS? Repetitions ("reps") are invaluable here. As you work through RTK, you'll be entering in the Kanji/keyword as you go. This manual entry, while tedious, can help reinforce your memory. After the data has been entered, you'll do reviews of the "flashcards", which are increasingly spaced out to help ingrain the content in your long-term memory. More information on SRS can be found here. Basically, if you follow this method religiously, it's pretty difficult to go wrong.
The bottom line: Don't skimp on, skip or half-ass this phase. Doing so can monumentally affect you in the long run. Pace yourself, get through it and you'll thank me later.