Kanji in Context (no link provided) and Essential Kanji (had to look up the title:
Amazon.com: Essential Kanji: 2,000 Basic Japanese Characters Systematically Arranged For Learning And Reference: P. G. O'Neill: Books) are both good. I've used both with success.
Pair these with the flashcard program Anki (or Mnemosyne) and some writing practice.
Although I think you will likely forget almost every kanji if you keep up 20/day for very long unless you review constantly. And I do mean constantly. I think 25/week is doable (I kept it up for a while with minimal study until the lack of studying caught up with me after I'd acquired an additional 400 in the first half of a semester in Japan).
I've since lost the ability to read and write most of them through lack of usage. Cramming works if your goal is to hit a point of knowledge and you don't care about retention after that.
By all means, if you're living a pretty much fruitless existence as a hikikomori already, basically the only thing that could hurt would be bashing your head against the wall 24 hours a day. Go ahead and try to learn the kanji. I wish you luck.