I've never in my life used that kind of workflow, and only use the pasteboard in a temporary way.
You should place those items into an InDesign library. Choose File > New > Library and drag them into the library. Then drag them out when you need them.
Use the pasteboard is an amazing feature!
1/ About your question, I've not this problem [ID CC 2014 tested].
2/ A [JS] makes jump all I have on all the other threads pasteboard on the current one (if don't touch the pages). One of a very cool "Pasteboard" tools set written by Marc Autret.
So in your scenario what becomes of excess text, which is in a linked text box and needs to accessed by an editor at a later stage?
Steve has the best option, but here is a workaround...although it's not very elegant.
If your overflowed text box or picture box touches the actual page edges - even slightly, they will travel with the page. The problem happens when you have facing pages and move a right hand page to a left hand position and vice versa.