Hi Yigit,
Before I saw your message I solved #1 – rediscovered the instructions for embedding the typography code into the Header file. And I restored the page to a version from three weeks ago, which solved the AWOL content issue, #3.

Then I saw your message about #2 – thanks, that worked :)

So it seems that the theme updating overwrote the changes to the header and functions files, which perhaps caused a conflict that then borked the whole page.

Thanks for your help!
Cath