3.1 update breaks featured images/imagery

The recent update has broken a few pieces of custom code for a client’s site I’m rather novice when it comes to reading, writing and understanding PHP so I was wondering if someone could help me out.

This first piece is supposed to display the featured image, but no longer does so.
[Code moderated as per the Forum Rules. Please use the pastebin]

This second piece is used for displaying the header graphics and doesn’t work in all browsers/barely works period with 3.1.

[Code moderated as per the Forum Rules. Please use the pastebin]