My advice is to not stress out over it. You really can't change what it is going to be at this point. Just go in as an educated visitor and gather as much useful info from those who have gone before you.
To answer some of your questions:
- You can purchase Genie+ in advance for every day of your package. Or you can purchase it on a daily basis, beginning at 12M the day of your intended visit.
- At 7 AM, if you're an onsite guest, you can purchase IA$/ILL$ attractions. You will be able to choose from a number of return times for those attractions.
- At 7 AM, all guests who have purchased Genie+ can book their first LL reservation. You will be offered only "next available" time slots for each attraction.
- Just like paper FP, you will not be able to have more than one Genie+ LL reservation at a time UNLESS the LL reservation that you just made is 120+ minutes away. In that case, you will be allowed to pull another LL reservation for another attraction for an earlier time slot.
- You will only be allowed to use Genie+ or IA$/ILL$ once per attraction per day. So if you buy ROTR for 10 AM, you cannot purchase it again for later that day. With Genie+ if you've used it to get a POTC reservation in the morning, you will not be able to get another POTC time slot later in the day.
There's no knowing at this time how quickly Genie+ or IA$/ILL$ selections will get taken. So much of it will be a function of how many Genie+ get sold and how many LL spots will be allocated each hour. My feeling is that the more Genie+ that get sold for the day, the more time slots Disney will allocate to Genie+.