Hello there!
Thank you for clearly stating the details of the project, not often I see that here.
Obviously, all the parts that you have mentioned are possible to implement. Although it would take time and some skill to do it.
Do I understand correctly that you actually need a published Add-on? Not just the system created in particular spreadsheet? Add-ons are designed for spreading the system to many people. If you just need people in your company to use it, it would be possible just to copy all teh files and connect them by IDs.
The setup of the admin email and the save folder will be implemented through the custom menu. So when you click an item a popup dialog will show up and let you type in the email, or choose a folder. The info will be stored within the script and can be changed by going through the same buttons in the menu.
One thing though, two different forms can not submit data into the same sheet. Once you tie the form to the sheet it will create a sheet for its own submissions. Not much we can do about that. So after submission of the forms we would need to actually copy data to the admin sheet through the script, while submission sheets will be there as well.
In terms of form change, if I understand correctly you only need to change the crew list, you aren't planning to insert new questions? if that is the case, it should be a straight forward process.
Creating Master sheet automatically may not be necessary.
Let me know if you are willing to talk
Denis