Oh my god!
You really must love kids. 
At least you are a responsible sperm donor!
As long you are OK with it I have no problem with someone having an future army spread out over the US. 
I think its great... Congrats on #4!
Aww, what a kind thing to say, D.O.A.!
No matter how you cut it, I've paid for literally 100% of all of my children's expenses from womb to present day. The only expenses I haven't paid is the food that they eat at their grandparents house. Even the food that they eat at their mothers' homes is ultimately paid for by me, as I pay all expenses, and give them $600 a month per child, which undoubtedly covers food expenses.
I do think this will be my last baby though...barring something unforeseen, that is. But I think four is sufficient. I'm quite looking forward to this next one, and my second youngest will have just turned three by the time the new baby is born. I think that is not a huge age disparity, and I look forward to the interactions of the two.