NO! you can not I looked up that it is a public affence.You can Carrie it in a suitcase but if you point it or let some see it purposely it is a public affence.
The range differs, it depends on your gun, and the fps, the higher the fps the farther it travels, mine goes over 100 yds (400 fps) some can go for only 20-30 yds it depends
Not normal 68 cal. paintballs but you can buy special 6mm paintballs intended for airsoft guns ive never seen one in stores so you might have to order them from online