How should I plan for additional Lightning Lanes? How easy are they to get?

We are going in September. Our first day will be in Magic Kingdom and I am considering getting Multi-Pass for our family of 4 (+ a free toddler). I'm trying to consider the best way to use it now because it's fun.

We have a Royal Table breakfast reservation at 9:10am. I'm planning for that to take an hour. Is that fair?

I want to try to book our first LL for some must see rides in the morning. This includes Winnie the Pooh, Haunted Mansion, and Tiana. I'd like to hit Peter Pan while we're going between Winnie and Haunted.

Should I book my Tier 1 LL for Peter and expect to get a spot on Tiana as an additional LL in the morning? Or should I skip Peter if the line is too long and keep the Tier 1 for Tiana?

How easy is it to grab these additional LLs day of? Can I plan on them or just grab what's available?