When Private Pair goes down, matter updates and document scraping from the PTO cannot be completed. However, this does not mean the updates and scrapes won't happen. AppColl continuously tries to update from Pair until it is back up and running.
Yes. There is a product called AppColl Tandem that allows for your client to have their own AppColl account (free of charge for AppColl PM Plus users). The Tandem account give them access to whatever data you wish.
When a page is locked, it means someone else is currently accessing the page. This is done to prevent two people from simultaneously editing the same page. There is an option shown by the page lock text to send an email to the person using the page. This option sends an email that someone else is trying to access the page.