Questions About Punping, Veins, And Full Package Pumping

I noticed a good amount of veins start to show up after I used a bath mate for some time and i wondered if pumping actually helps vein development. I stopped pumping and decided to get into a stretching oriented routine and i noticed more smaller veins right under the surface of the skin start to show up. I plan to start using the bath mate again for just 5 minutes before and after the workouts. The pumping seems to work the larger veins that typically appear green for me and the manual exercises like stretches and jelqing tend to work the smaller veins that appear purple.

I was thinking that while i was in the pump, I might as well consider full package pumping to give everything downstairs more blood flow. I read around about full package pumping, but there isnt much discussed about it. One reason why i stopped pumping in the first place, was because the vacuum seemed to over flow my CS and glans with blood. It made them expand a lot after i took my penis out of the pump, but later throughout the day and days following, my glans would be weak and my CS would be more flat. That was from when i pumped for 15 minutes before and after the workout 5on/2off. It even happened when i pumped 2on/1off, so there was really no difference.

Are big increases in vein size without the pump possible?
Does smaller CS and glans mean i’m over working in the pump?
What are the benefits of pumping your entire package(Penis/Balls)?