Is the billfold divided?

The wallet is a tri-fold. When opened up it is about 9 inches long and is 4 and one-eighth inches wide. When opened up it has a divided space for folding money, so some could go on one side of the divider (which is cloth), and some on the other. It is a perfect wallet for me. When folded up as a tri-fold, it fits my butt good and is wearing very well without becoming deformed. The leather is soft and it has a tooled emblem at the bottom corner so I can always easily orient it to go into the pocket the right way. I have had real stiff and hard leather wallets in the past, and while I may like the look of them they aren't comfortable like this one is. I don't think anyone can go wrong with this wallet, especially for the price.

Can you attach a chain to it?

This wallet does not have anywhere a chain can attach to.

does this wallet have a velcro closure

No Velcro (or other) closure. I think it is better without. The tri-fold was new to me, but after carrying this as my primary wallet for several months, I really like it. It is easy to "overstuff" but otherwise is well mannered and is no problem when in the pocket. Sometimes at home I put a rubber band around it, but when carried in the pocket as a wallet there is zero problem. The leather is high quality. Best wallet I have ever owned. If you try it, I think you will like it in actual use. The Velcro would add bulk, and it never comes open in a pocket. So my vote is better without Velcro.