OLED sounds great, but from everything i've read the way burn in works is different from plasma. In that it's going to burn in with the same elements on the screen eventually no matter what you do or watch in-between. A thousand hours is a lot so it's not going to happen with a game, but I use my TV as a desktop monitor. I don't have an issue with this with my plasma as I switch stuff up often enough, but I'm concerned with doing the same with OLED.
By most accounts, current OLED TVs are more resistant to burn in than plasma—though this will depend on how it's used. There are certain features that can reduce or delay the occurrence of burn in on OLED TVs that plasma didn't have. Using OLED as a PC monitor ups the risk only if you're using it to do regular PC tasks. If you're just using it for gaming and media viewing, then it's not an issue. If you didn't have burn in on a plasma under these circumstances, then you'll probably be fine on OLED too. Also keep in mind that it isn't a thousand hours per se, but that thousand (or usually several thousand) hours refers to cumulative hours of the same static content displayed over time.
I used to have sharpness at 10 for the longest time and then someone said it should be set to 0 so I changed it to that. Is there anything I could use to test that setting?
For the 2018 and 2019 LG OLEDs, the Sharpness setting behaves differently depending on the context. At a value of 0, it's completely disabled in every instance and is generally the correct setting. A value between 1-10 will actually not add any sharpening, but instead apply a form of antialiasing to anything below the TV's native 4K resolution; if you send the TV a 4K signal, then Sharpness will still be disabled at 10 or less. The anti aliasing can remove certain artifacts caused by the TV's scaling, but it can also cause other artifacts and make the picture a bit softer in certain instances. A value of 11 or higher isn't recommended as turns it into a traditional sharpness control and adds ringing to the image with any signal.
EDIT: The sharpness pattern in the link holygeesus posted is a good tool to figure out the right setting. Just keep in mind the setting you chose based on that pattern will only be applicable to 1080p or lower resolution content.