Advance Parole

Hey guys, I'm looking to obtain AP and currently in the process of preparing/gathering documents needed. I'm planning on filing for a humanitarian reason, to visit my grandma. She's not in a critical condition but she's been in a long-term care hospital for some time now. My grandpa had also been through cancer a few years ago - the surgery went well and he, too, is not in a critical condition at the moment but considering his age (in the 80s), I'm always worried about him. Between school and jobs, I haven't had the time or financial means to travel, but I'm graduated now and have some break until the end of this year, between switching jobs. So basically, long story short, I'm planning on explaining all of this in my AP application, but I was just trying to see if there's any advice I can get from those of you who have been through this already.

My official reason is to visit my grandma - as it probably would be easier to obtain an official evidence, like a doctor's note, since she is actually in a hospital. My main question is, those of you who were in a similar situation as me - do you know how detailed the doctor's note has to be? I'm thinking it'd be helpful to give the doctor some pointers so he knows exactly how to write the letter. And what's your experience with providing a proof of relationship with your non-immediate family members? Also, if everything gets approved with no problem, the duration of your AP is the intended dates of travel you fill out in the application, correct? I know with the current political climate it could be risky but I'd like to travel from mid October to December. If I hurry and submit my application before the end of July, do you guys think that would be sufficient time? What happens if the AP gets approved past my intended travel dates?

Sorry for so many questions - I wasn't planning on applying for AP until pretty recently and I need to travel before the end of the year so I'm trying to make sure I prepare everything perfectly. Thank you guys so much and I'll keep you guys updated on my application process.