You should give an accurate price range for what you are looking for on your post, as that is what people generally look for when deciding whether to pursue it or not. I recommend to add at least a price range, since it will significantly help you in getting designers. Good luck!
While some do, from my experience most do not like haggling over the price. My suggestion is to just give them a range that you can then decide if you want to go lower or higher on the range based on their skill.
You should be the one providing the details on how you want the game icon and thumbnail to look. Most graphic designers also don’t know what makes a game icon get a good CTR %, so that’s why you should be the one who’s coming up with the design.
