Hey @Maruvail! Good questions all around, I hope to hit all your points, but feel free to follow up with more if I'm not super clear.
What is a prop exactly?
Props are a bit loosely defined because of how much they encompass. I guess the best way for me to explain it is you have a bunch of "physical" components to a Tale; some of them are Locations (pretty self explanatory), some of them are Characters, and some are Props. Characters have autonomy, where Props don't. Something in a Tale might be a Prop where in another it might be a Character. E.g. A legendary cursed sword might just be that in a Tale (a Prop), but in a different one, you can "inhabit" it as a player and have it talk and shoot laser beams, now that it's gained autonomy.
Props range from tools and weapons to vehicles, to furniture, to spell scrolls, etc.
Do we need to talk about specific items in our submission in order to qualify for these points?
First of all, I would like to say the points and the point system isn't quantitative in that sense. A 60-point Tale isn't any better or worse, or more or less deserving, than a 100-point Tale. And as such, it's not going to get benefitted or damaged by having a different tally.
We have that minimum as a bit of a filter to only have stories where authors went in depth in at least some of the categories, not necessarily all. Once you've met the threshold, the criteria that will be important to select a Tale over another are: popularity among members, creativity, originality and diversity of themes.
The reason Props are separated and given separate points, is to be able to properly reward and keep in the running Tales that are focused around those. If you have an amazing story that revolves around giant mecha fighting each other, you're probably going to go into a lot of detail about the different types of mecha there are, and get a lot of Prop points in the process; allowing you to not go into as much detail about Locations or Characters (maybe you want to just let people bring their own, as long as they're mecha pilots).
That said, if your story has cool items and you wanna go in-depth about them, you're more than welcome, and we encourage it, but it's not necessary. It's more of an opportunity to give points where they're deserved than a checklist item to cross off for contestants.
Would unique monsters or plants qualify for this section?
I would say it depends on the context, like I said with the sword. Monsters will probably more likely be interpreted as Characters, since they have autonomy, and you could have a player playing as an ogre, or controlling all dragons the party encounters.
Plants could be Props for sure, especially ones small or frequent enough to be Props. I'm thinking the concept of a forest or even a giant tree might fit more into Locations. It's really more about the context and its role in the story than anything else.