
YA FOR 11 DAYS!!! Guess what...11 days for me too!!!!
I did online check-in once. My brother and I took a last min trip in March and we stayed at POP. I figured I would do it to try it. Of course it worked fine. I said I'd like building 6 and we got building 6 on the highest floor so I'm not sure if we didn't get it, what would have happened. I haven't done it prior to that or after that. I don't have kids so to me, I don't mind standing in line and having it take a few extra mins. I think for some people that takes away some of the beginning of the trip fun but for others, I can see how online check-in is a life saver!!
I'll ask my friend who works concierge at CSR and see what she says. I've had room keys re-cut all the time. We had to have them re-cut in Oct because they didn't have charging on them and we wanted charging. As far as reassigning a room, I'm not sure? My mom went in Sept and asked for building 10 at POP and were given 6 which is across from 10 so it seems they try to accommodate even if they can't give you the exact building..maybe?
I'll send her a message on fb and let you know! I don't think we're going to do online check-in. I'm staying the one night at POP and then 4 at WL. I actually need to call to see if the requests were put in because when I did call, the CM asked for the # for pop, took the request, asked for WL request without the # so unless they are linked by last name, I doubt my request for WL was put in.

I'll get back to you on what she says!!!
UPDATE:..I sent my friend a FB message and I'll let you know when she gets back to me. Shes working 11 days straight or something crazy so she might not get back to me right away this morning but I'll let you know when she does!
UPDATE AGAIN! I talked to my friend and she said that if it's the notes and the space is open in the room they try to accommodate requests. She said to call WDW if you have time and confirm the room request. I actually just called to confirm mine and everything was set. The CM I spoke with was soooo helpful and said that once you have one reservation they are all linked even if they are separate so if you made a request at POP and POR, she will see them both on the same screen to confirm the room request! She was able to see my room request for the 9th at POP and 10-14 at WL. As far as online check-in, you could do it but I would make sure you confirm with WDW that your requests are already entered before you check-in. She said if the request isn't fulfilled at check-in and they have space in the building/floor that you want, they can move you but it will make the check-in process longer because they will have to shift things. She said the request isn't a guarantee but some people don't request at all, some want a certain floor, others want a certain building so they are usually able to accommodate assuming they aren't sold out. I hope that helps!!!