As for the age of your FR's and how big they're going to get - I just finished 25 FR's. The last were 11wks5days old. They were hens, and none were larger than 7#'s. The last roo I did at 11wks2days, and he was 8#'s live, 4#8oz dressed. So yes, big, but not impossible to deal with.
As for processing - yes, you'll need a LOT of freezer/fridge space. The 8 I have in my fridge are taking up 1/3 of the space! (Note to self: get chx in freezer today!). However, it's not impossible to deal with. Knowing you're in a spot with likely a lot of folks, think about processing two or three at a time for a special dinner for all - a way to say thank you to SIL and her family.....besides if you end up there for a while, you'll need the meat! Consider it your own grocery store - fresh eggs and meat for a long while! Thanks to the powers of this forum and youtube, DH and I figured out how to make our own cone, set up our own processing station in the garage, keep everything sterile and clean, I'd find the next 'contestant', DH did the deed, we both cleaned birds, I packaged for the freezer and we did it. It's truly empowering to know that yes, indeed, we can do this! Grandparents did, why not us?!
As for the crowing, we said 'if you crow, you got to go!'. The first ones didn't figure out a 'true' crow until just after 10wks old. Before that, it sounded like a french horn with a mute in it! Funny, funny stuff! However, the first two who did figure out how to crow became dinner. After that, none of the other 12 made a peep! It's like they knew what happened and why!!!
Ours were so funny - they KNEW the pink wellies brought food, and so whenever pink wellies showed up in their yard, they came CHARGING at me! There were times I couldn't get through the gate because they wouldn't let me through! Didn't matter if I had that evil garden hose (to refill waterers) or not - they gathered around me like I was a rock star. My layers haven't ever given me the time of day - much too haugty to do much than lay eggs and peck the ground bare - but the Rangers were really beautiful, friendly even gregarious, happy critters. Yes, I miss them, but I'll get more in September! I may try to figure out how to keep some through the winter, as they are such wonderful birds. (But don't mention that to DH, ok?!)
Best wishes and prayers for safekeeping....for all of yours.....