Shipping is included. I prefer DHL over UPS. You have a choice.

Just put down for two more on batch 5. I bet Bitmain is betting on another few rounds of low difficulty jumps to justify the slight decrease in price between batches. Judging by how much of the network they can control when they batch test, I'm going to bet the price is probably in line with expected network growth.

It all depends on how you calculate your ROI. If you have a bunch of equipment that's already paid for itself, you can choose to calculate that hash towards your most recent purchase and write off the hardware much sooner. Much easier to calculate any gains down the road that way.

...it also might involve a little bit of lying to yourself too, but trust me it's much more fun this way.