Heya Amy,
The devil might be in the detail, but I think you're right, this idea of yours could make the first chapter, well, a first chapter! It's definitely not the easy way, but then again, no one ever said writing first chapters is a breeze. LOL But I actually like your idea. Heaps. It would keep the reader in suspense what the hell Catherine was doing there etc. etc. (and all the things you've mentioned). <------ I'm stubborn, yet open-minded! WTF?
I'm fast running out of ways to thank you, and others, on this site for all your wonderful suggestions and ideas and support ... But in any case, a big thank you for investing in this and all your help/support!
I've also been thinking of ways to only have her move her arm after a week, but Matthew isn't a virtue of patience, so, so far, I've only been hitting walls (he's also not incompetent, so them taking a week or more to find Isaac is also not going to happen!). And I don't want him to be an abuser - if she's that badly hurt, he won't lock her up or do anything more than asking and yelling. But I haven't completely discarded your opinion yet ... (just so you know!) It could actually also work out better later on if she actually did hurt her arm really badly. But I'm still thinking on that one. Having her arm in a tight sling to keep it from moving is what I have for now. *Yawns* If all else fails, I'll put in a disclaimer for all ER professionals that Amy told me so and to just go with the flow! 
Re your other thoughts, absolutely, I keep all of them and do make changes based on those kinds of feedback. So when I explained to you about the size of the towers and the bathing, I actually meant to say it will be expanded and those kind of details will be worked into the scenes to make sure there will not be any confusion again. So that kind of feedback is really great to smooth things for others! 
ps - Matthew isn't happy with you (and he has a sword). He was 1-inch away from getting some nooky when I saw this post, and now he has to wait until I've redone the first chapter before he's going to see (get) some action .... LOL
I know what you've said about getting the first draft done, but given it's a big change, I'll interrupt the flow to do it now, otherwise I won't be able to concentrate on writing the rest of the chapters ... I'll just wrap up the chapter I'm busy with now, go back to START, don't collect $200, and then I'll be going again on the rest of the story soon. 
I'll probably repost the first chapter, and then I'll review some work for njc, and that way, someone would have a good look over the reworked chapter. <----- that's the plan for now, at least!
Thanks a mill for this!
Janet