I suspect a sticky with the basics would answer a lot of questions. Now that some loopholes have been closed, the process seems to be much clearer than it was at first.
Here are some things that might be included:
1 - Genie+ has a daily fee, but does not give
Lightning Lane access to all attractions. Lightning Lane is simply the new name for the Fast Pass Lane.
2 - ILL$ is the name for the extra pay attractions (currently 2 of them in each park)
3 - Genie+ can be purchased in advance for all days of a resort stay. For individual days it must be purchased day-of (can be purchased as early as midnight)
4 - Genie+ allows selection of first Lightning Lane attraction at 7am for everyone
5 - ILL$ allows purchase of 2 extra pay attraction Lighting Lane access at 7am for WDW resort guests only; non-resort guests cannot purchase until park opens
6 - ILL$ allows you to pick the desired time for the attaction; Genie+ only allows you to pick the next available time
7 - When using Genie+ to see next available time, you can refresh to hope for an earlier or later time; occasionally earlier times will pop up.
8 - When you make a choice, the time MAY CHANGE (usually to a later time) by the time you hit the Confirm screen, so be attentive!
9 - You cannot modify a time once who have confirmed; the only way to pick a different time is to cancel what you have and then rebook
10 - You can have LL access only once per attraction
11 - Genie+ will tell you when you are next eligible for a LL. You are eligible EITHER (a) 2 hours after park opens, or (b) when you double-tap into the LL you most recently booked (if sooner than 2 hours)
12 - Speed is important for a few 7am bookings; pinning the desired attraction to the top of the attraction list is helpful (explanation needed for how to pin it there)
13 - Play around with the Tip Board before your trip to get an idea of how it works
Information needed for park-hopping to 2nd park, but we never parkhop, so I haven't really been following those procedures.
Questions about who all can be booked probably need to be addressed (everyone linked in the Friends list etc.?, everyone must have park reservation). You can select different attractions for different people (just like for FP+)
I'm sure there are other basics that I'm not thinking of off the top of my head, but I hope these suggestions are of some help. Also, I'm sure I've said some things that need correction or further explanation.