You might want to see if you can get your hands on a copy of A Guide to Remembering Japanese Characters. It explains the actual Chinese origins of Japanese characters, not just convenient ways of remembering them, and how they were adapted into the Japanese language.
First off, thank you for sharing your personal background.
If English is not your native language, yet you are striving to learn a third - honestly, I can't send enough kudos your way.
As far as kanji is concerned, I highly recommend A Guide to Remembering the Japanese Characters: https://www.amazon.com/Guide-Remembering-Japanese-Characters/dp/0804820384/ref=sr_1_1?ie=UTF8&qid=1501029816&sr=8-1&keywords=a+guide+to+learning+the+japanese+characters
"Remembering the Kanji" seems to be far more preferred, but me, I've found that learning the historical basis of the kanji has helped far more than mnemonics that may be counter to their actual origin. Again, that's just me - everyone is different.
tl;dr version - Looks like you've decided to start learning Japanese and join the group that may have other people looking at you weird. Ignore 'em. We're glad to have you. :)
> 日本語の勉強を始めたのはいつ頃ですか?また、それはなぜですか?
10年前かな、13歳の頃。最初に、ただニンテンドに興味があったから勉強したがどんどんと他の日本のもの(音楽、アニメ、アート)と日本語自身にも興味が増えてきたんだ。
> どのように日本語を勉強していますか?(大学、語学学校、テキストで自習など)
ずっと、殆どの場合、自分だけで勉強しています。イギリスの出身なんだがあそこで日本語の授業がある学校は珍しいよ。それでテキストで自習しかなかった。とにかく、漢字は自習するしかないね。大学に入ったら、Japan Societyというサークルに参加したのでよく会話の経験を楽しめた。現在、一年間で中学校の英語先生として東京都に住んでいるから日本語が上手くなっている。
> 主に使っている教科書やアプリ、ウェブサイトなどを教えてください。
よく指されたTae Kim's Grammar GuideとGenkiのシリーズ。高級の文法は、「新完全マスター」のシリーズが大好き。漢字はHenshallのこの漢字語源辞書も神のものだ。
> 勉強以外で日本語を読んだり聞いたりしていますか?(漫画、アニメ、音楽、ニュースやブログなど)
漫画とアニメは読めますけどニュースはまだ届けない限界だ。
> 5. 日常的に日本人と日本語で話したり日本語の文章を書いたりしていますか?
うん、よくする。フェイスブックで何かを書いたら、英語はいつも日本語とともに書く。
As far as uniqueness of the project goes for etymological sources on the origins and compositions of characters, there is also Henshall 1995 - A Guide to Remembering Japanese Characters, although it only has about 2000 entries and obviously it is geared for how characters changed over time in Japan, not China.
If you decide to go the route of memorizing individual characters first, I highly recommend A guide to remembering Japanese characters by Henshall. It's a more academic approach to Japanese characters. Some of Heisig's key words for the primitives make no sense at all. Make your own mnemonics though because his suck.
Not sure how fun it is, but Henshall's book has good etymology explanations for all the kanji.
I learn Kanji with the Kanji Study app and with Henshall. I make my own groups (here's an example). I am nearly done; all common-use are now at least tentatively reviewed.
I am currently learning vocabulary by reading Japanese Graded Readers. I make my own vocabulary lists (example), but I don't really review the list: I make it (thus getting the words/phrases I don't know) and practice by reading the book. When I was doing a textbook, I'd use their vocab lists. The Graded Readers don't provide it, so I make my own. It's good practice.
>I don't know of any decent online sources for looking up Kanji etymology
Do you mean, in English? Because this right here is a fantastic (all-Japanese) resource: https://okjiten.jp/index.html
Literally the only English-language resource I've kept over the years has been this bad boy: https://www.amazon.com/Guide-Remembering-Japanese-Characters/dp/0804820384/ref=sr_1_1?ie=UTF8&qid=1503974276&sr=8-1&keywords=a+guide+to+remembering
Old-school, but nonetheless phenomenal.
Kanji is actually the easiest part of Japanese.
For eight months your above is pretty good! Much better than me after 8 months.
What really helped me was finding:
http://www.amazon.com/Remembering-Japanese-Characters-language-library/dp/0804820384
the tldr with that is to learn the simpler characters before the more complicated ones, and build imaginitive stories.
But these days with computers the best way to learn is to just read, read, read, and get rikkaichan or whatever to help you with the readings and meanings.
http://www.popjisyo.com/WebHint/Portal_e.aspx
also does a good job. I was supposed to finish my Japanese language iPad app last year but I'm a lazy git, sigh
There's only 3000 or so kanji you have to learn. 1000 are piss-simple like 日, another 1000 are fun combinations like 独 -- beast + bug = alone, pretty easy to remember, the other 1000 are harder to keep in your head but as long as you learn them with an actual word or two keeping their reading(s) and meaning will be easier, and if you forget this last category don't worry too much because the ones you forget are the ones you're not seeing that often . . .
Again, the important thing is to read a lot.