When can I select seats and question about timing a connection
 

Looking for some advice...CODESHARE AA & Timing to take domestic connection

I have an August YYZ-ORD-NRT codeshare booked through AA. JAL flights are "O" class
Two items:
1. I have read the forum for past (which seem dated) on this and spoken to them and I have different answers as to when I can select seats for me and my 2 kids. One answer is that I should be able to do it with online checkin on the JAL site at T-72 with their Confirmation code# instead of AA's, while another person there told me they will be assigned on check in, but it could be that I have to arrange them at a JAL desk after arrival in ORD. (which is an awful ideal) Does anyone know definatively?

2. I have decided I'd like to connect to Osaka after landing in NRT. The flight is in the same terminal scheduled for 1h 55m after my scheduled arrival. JAL sells this flight combination out of ORD and I understand you need to pick up bags in NRT anyway so not a big deal that they are not ticketed to final destination, but my understanding is that JAL may not consider them as connected and may not take any responsibility if the flight is late. I have read about requests to combine PRNs but with a codeshare and what I perceive to be JAL's not so positive approach to flights they have sold through codeshare, I am concerned about getting any help from them. Any ideas/ thoughts about the connection?

I've tried to call JAL 4 times and been on hold for over 20 min or found that they had closed reservation lines.

Thanks in advance.

1. seat selection available at online check-in on the JAL site at T-24 (not T-72)
2. JAL will not consider them as connected and will not take any responsibility if the flight is late.
However, they can (and most likely will) check your luggage through all the way to Osaka (as it is a JAL-JAL connection). You will need to update your luggage tags at ORD, so go to the transfer counter/check in counter as soon as you land from YYZ. 1hr55min connection at NRT is easy to make, and you should have no problems should you not have the chance to check your luggage through to Osaka.
Make sure your flight from NRT to Osaka is on JAL, not some LCC or ANA!