Hello there! Welcome to TPF! The birkin is a great bag for a guy. 35 or 40 both work but I agree a that you may need a 40 to fit all the items you listed. However, I would never recommend a birkin for everyday/school use. Firstly, for me personally, I don't want to risk any damage to my birkin and I feel having too much weight from papers, folders, and a laptop will definitely put a strain on the bag. Some folks do it, and most of the time its fine since the birkin is super durable and well made, but for me personally, I wouldn't want to use my bag for that, especially with the cost of it haha. I actually recommend the other models which I think fits more and is lighter for daily use. I use the Victoria and its a beautiful bag that has proven to be very efficient for me.
What I notice when I put my school books, folders or laptop is that it sorta bends the base of the bag across the middle horizontally due to weight and leaves an indentation on the interior which bothers me.
Birkin 35 and 40 are very heavy bags because they are leather lined and just really well made, and putting in more stuff will make it VERY heavy especially as a top handle. The perk of the victoria is that you can wear it on the shoulder, plus its much lighter since it is fabric lined. I have a 30 since I am shorter, 5'7", plus I wanted a smaller top handle bag for more planned outfit days like brunch or fun in the city, weekend stuff.
But also, go with what your heart desires! If you are dreaming of having a 40 to use and love everyday definitely go for it! The birkin is really a great bag!