I personally found Heisig's RTK (vol. 1) to be quite valuable. The important thing to remember is that it doesn't teach you any vocabulary or grammar - it's simply really big mnemonic for learning to write and recognize the characters. You should certainly get the book in your native language if it's available in that language.
Your English is fine, for all I can tell you may even be a native speaker; but it's much easier to remember mnemonics in your native language - if you're going to learn mnemonics in a foreign language why not just go straight to Japanese? --- which is an option, by the way. People have used the RTK system with Japanese keywords when they already knew some Japanese to start with, just not how to read and write.
Anyway, as it is just a large mnemonic system, if you combine it with flashcards, don't obsess too much about reviews; remember that it's allowed to put hints (or even your whole 'story') on the front side of the card - the question should be 'can I recall this character?' not 'can I memorize which synonym is abitrarily paired with which character?'. People waste too much time on that stuff. Just put extra info on the front of the card so you don't mix up synonyms.
RTK3 is just an extension of RTK1 into less common characters - not to say you won't encounter them, especially if you intend to read novels or histories or the like, but RTK1 includes the vast majority of characters in the JLPT tests. RTK3 is kind of overkill and you should only use it if you really want to know 'all' the kanji. (It's still not 'all', but it's all that you're likely to encounter in non-specialist reading.)
I never did and don't have any interesting in doing RTK2. I don't have any problem with associating characters with words now, and I can identify phonetic groups for myself or by searching on the web. Still, some people love this book. It just smacks too much of the kind of useless 'kanji reading' study that I wasted too much time with in my early attempts to learn the language. It does give examples of real Japanese words for all the kanji you've learned in RTK1, and even though there are other ways to learn about it, having phonetic elements listed out for you is good too.
As an aside, I would use 'smart flashcards' from an SRS program like Anki or Memrise rather than paper flashcards (and -definitely- over a 'dumb' flashcard program that keeps feeding you all the cards every day just like they were paper).
Of course, it is also possible to do spaced repetition with paper cards, as long as you keep them carefully sorted. I'd rather let the computer take care of scheduling for me.
Spaced repetition - Wikipedia, the free encyclopedia
Oh, as for the poster... get whatever one you like the look of best really. Kanji posters are not effective learning tools, but they are (for some people) effective motivation tools, because as time goes by you can recognize more and more characters on the poster.