Few questions regarding creating threads on forum

Hello,
First of all, i would like to apologize if there is already somewhere i can find this info, and i am asking here, but i haven't found.

That being said , i want to make a really nice thread for guild recruitment, and what i need to know is:
WHat is the max resolution of the image (both max width and height) that can be linked and displayed on thread without being resized?
and
Amount of images i can post on single post?

Thank you for your time consumed reading and in advance for any help i get.