Well, first of all, good luck. Having a director with any other hat as well always has its challenges!
As for rewrites...I'd find out if you are to be the one in charge of keeping the script updated, or if he or someone else is (though it's more work, I'd be tempted take it on in the stage mgmt dept, so you're sure it's getting done). I do several things in my script...any time there's a change that you write in, write a date in the margins so if there's a question you can say when it happened. And if it's reinstated (cut once, but then decided to put it back in), I write that too, and both dates. Keep a separate script handy that is the master script with all changes, so you can make copies if needed for someone, or someone else can grab and see if they got them all, etc. And best one to prompt from if you have an assistant, etc.
I also keep an Excel file table going of script changes, particularly little oneliners. It often gets frustrating (both for those doing it, as well as those receiving) to make new script pages for every single script change...you can then pass out or post or email this chart to folks, who can fill in their own changes in scripts. And if it's major, of course new pages are good...I often end up with something like "Page 75B" if your new stuff is bigger than the old one. And of course put the date on any new page, for clarification. As for the Excel file, I'll list columns of page number, change (with words like cut, add, substitute, or change order in this column to describe what's happening differently), and then the line, starting with the character's name in all caps. If something is cut, I'll use the strikethrough font feature, if it's added or changed I'll both underline and bold it. I used to have a separate column for character who said the line, but if you just put it in the line section, it's easier to use when you change the order of several characters' lines. I can email you a version for clarification if you like. OH, and if you don't know about the shortcut in Excel, if you hold down "Alt" while you hit "Enter", you can add a hard paragraph break within a cell. Very handy. I know there's something similar for Macs...
If you have sign interpreters, don't forget to give them the information too!
Hope this helps,
Erin