I'm planning on getting the the Globe Plan 1799 with iPhone 7 Plus 32gb. Since this is my first time acquiring a plan, do I need to pay the cash-out on the spot to avail the phone and plan or can I pay it monthly on top of the plan bill?

Additionally, since we don't have internet at home and I'm going to use this plan as my internet provider, if I max out the plan 1799 of data only and the antishock bill activates, what is my maximum bill payment that includes the monthly cash out? I really need the estimate per month.