Meter- 8x10 film is too expensive to guess with
Dark cloth-big towel works in a pinch and if you are a bit on the hefty side a sweat shirt will too. Skinny people don't have this option
Filters-I think they are necessary
The most important thing to do with 8x10 or any LF camera for that matter is to actually have loaded film holders when you want to take a picture. I have saved lots of film by going out on a trip with empty film holders. It happens to more people than you would think.