INTO THE AMLong Sleeve Tee Shirts for Men S-3 XL - Men's Longsleeve Casual Work T-Shirts

Is this shirt too heavy to wear as an undershirt?

Are newer versions of the shirts, specifically the long sleeve, made out of a different material? Because I bought one of the long sleeves a couple of

Do you have any other sizes other than small?

I am hoping at that price its more than one as I perfer to buy clothes in bulk, so how many are there per order?