Yeah, Genki has been really great so far. I should mention that I have the workbook AND answer key as well, both of which are great. The answer key also has all of the audio from the CDs in written form so its a huge help if you want to start doing some shadowing.
Another thing I do that is probably just as important as the Genki book itself is using an Anki deck that is based on the Genki books. It really helps to solidify vocabulary and the grammar structures that they teach! I just use it for EN-JP production of vocabulary and grammar. I can link you to the deck I have if you are interested, or there is also one that someone on these forums made that you can easily search for.
The Genki Answer key is a separate book meant for teachers to correct student assignments, but you can buy it yourself online. It covers both Genki 1 and 2.
Anki is free as a computer application or on a web/mobile browser but it costs around $20 for the mobile app. You need to download the computer application and make an ankiweb account to make it work. Probably best for you to just go to apps.ankiweb.net and start reading about it.
There are other applications that might work better for you than Anki. HouHou and Memrise are a couple that are often talked about, I think. I don’t know anything about them though. Anki is by far the most customizable SRS out there though, but it also takes the longest amount of time to learn how to use.
I thought it was great reading practice, and really liked that you can sync your WK API to toggle kanji you already know and also have the option to toggle furigana
There are lots of different articles and stories too so you can find a lot of reading practice there along with explanations of vocab and grammar, and they fairly consistently add new articles ^^
That being said, the difficulty does vary, so I’d recommend signing up and reading the free articles (the first 2 articles of each series is free) and seeing how you like it — that way you can get a feel for it and decide if you find it worth the subscription
Precisely, a fast level is a level where there is enough kanji that guruing the radicals and the kanji from the beginning of the the level is enough to level up. I believe the entirety of levels 50-60 are like that, level 26 and possibly 1 or 2 more.