The answer to your pagination problem is to insert section breaks and set up
different footers for each section. Your problem i) suggests that you have
checked 'different first page' under File > Page setup. Create a new
document, add some rubbish text to make it run to several pages, insert some
section breaks, and experiment with the footer settings, including 'same as
previous' on the Headers and Footers toolbar: ten minutes research should be
plenty for you to grasp what's going on here.

But before you go much further, I suggest you check the publisher's
instructions carefully. They don't quite make sense as you give them. If
you've been asked to double-space, that suggests that the publisher is going
to re-work the manuscript anyway; in which case pagination is their
responsibility, not yours.