Yeah, I did the same for my rp's interest check in making it appear more fleshed out. It was basically an IC post to help demonstrate and show the kind of characterisation, atmosphere and world my rp was going for, rather then being a bit cut and dry and just showing ooc esque information. It had... personality. 

I also think pictures are good so long as they're not gone overboard, as they help to inspire and get imagination going. 

Text formatting is important, and the relative aim of interest checks is to keep things simple. You don't want massive walls of text that make it hard to digest and unappealing to look at from the start. As for the ooc, I'd also suggest keeping large chunks of details in hiders to help break things up and make it easier to digest, it really is easier for the player that way. Another piece of advice I have is to be mindful of how much information a player really needs at the start of an rp. I've seen a few interest checks/ooc which go way, way, waaaaaaay overboard on the amount of detail and just present an awful, awful lot of text and information that needs to be read and learned, and there's not a single bigger turn off then that. Considering the vast majority of rps die quite quickly, I'm turned off with the idea of having to learn a vast amount of detail and lore for an rp that may not last long. Personally, I prefer to incorporate and introduce relevant pieces of detail in the IC where and when it's needed (better to show then tell and have it affect the characters at the same time) rather then go overboard at the start.