Missed the last one. Let's have a rat general thread!

Optional questions for anons;
>Plastic or iron cages?
>What kinds of tricks have you taught your rats?
>Have you ever made a toy/decoration/house for your rats? (If yes, post them!)
>What is the most amount of rats that you've owned at once?


I also have some seperate questions regarding pic related. I've been interested in buying rats for some time now; I still have a lot of researching to do before I make up my mind, but it looks like it may well happen in the future.
I noticed that this rat's ears are very red. Is this normal? Perhaps it was the lighting of the photo..
If I do go through with it, he will be bought alongside his brother- the owner had developed an allergy and wants to sell them, despite them being only 4 months old (owner did not list weight).

Is it an absolute dealbreaker if I find out that they were bought from a commerical pet shop? The owner listed them as "tame, clever and very cuddly", so there's a small chance that they may not be at that age.

I'm also planning on making a 30-40cm wide 'house' for them to go inside the cage (it's a large cage) out of wood; three walls with two holes on the sides, and a hanging drape to cover the front. I've read that wooden bedding causes respiratory problems, but is wooden furniture okay? Also, should the window be a circle or a square shape? Circle would be harder to do, but I'm worried if they might have a higher chance of getting stuck in a square-shaped hole as they grow bigger.

Thanks in advance, and sorry for my blatant amateur-ness. I hope to become a proud owner of two rat brothers soon.