Having been reading posts on the forum for the past few weeks, this is my 1st post, so 'Hi there'

I'm about to start my second brew, Coopers IPA, as it comes highly recommended from forum members. However, I'm slightly confused by the instructions supplied. Also, this is my 1st single can kit (my first homebrew was a Woodforde's Headcracker two can kit), and am slightly unsure how to mix the additional ingredients in when I start things off (I'm using 1kg DME after reading good things about it here).
How I understand the kit instructions, I dissolve the can contents and presumably the DME in 2 litres of boiling water, put this in the fermenter and make up to 20 litres by adding 18 litres cold water to achieve a temperature 21C-27C. Is this correct?
What then confuses me is that the instructions then say to top up to 23 litres to get temperature within the range 21C-27C, then add the yeast (presumably by sprinkling onto the wort?)

I had thought of adding some hops at the start too, having read on the forum how to do this - was going to follow DaaB's suggestion of boiling up 10-15g in the can rinsings, then cooling, straining the cooled hops and adding the liquid to the wort (did I understand this correctly too??)
Apologies for all these questions and sounding like a newbie (which I am

Cheers,
Shaun