Try to make sure you have all of the fonts used by the PDF installed on your system. I tend to only make small changes, but not having the correct fonts causes issues for me.

LibreOffice Draw can make changes to PDFs.

Seems to be a Monotropa. Common names include: Ghost Plants, Indian Pipe, Corpse Plants. It is vascular.

It looks like central California foothills. Lots of current fires, especially in Socal. Cal Fire