As long as you don't order like 20 at a time you'll be fine. I've ordered four times and neve had any problems, although one time the tracking number they gave didn't work but I still got the order eventually anyway. They only seize them at customs if you order enough that you clearly intend to resell.
As far as quality goes, what you see is what you get. If you notice a flaw in a jersey in the picture they have online it WILL be there when it comes to your door. I only order jerseys if there are no noticeable flaws in the picture and all the jereys I have received have been great. The Van Slyke one looks fine to me but someone else may have a sharper eye.