The sugars in extract have a dramatic effect in hop utilization. If you reduce the sugars you have in your boil(SG) it will increase the amount of AA that is extracted from your hops and vice verse.
Unless you have a problem burning your wort when you add the ME after steeping add it all at once. There really isn't any reason not to. The less variables you have in your boil the more consistent your results will be. Keep your recipes as simple as possible to produce the result you want.
As far as your hop sched. get rid of your 45 and 30 min additions.
use your 60 min additions to hit just below your desired IBU
Bump up your 20-0 min additions.
Dry hopping will add flavor and aroma to your beer. 2-4 ounces seems to be the sweet spot.
IPA's are difficult to give advice on because intensity of hop flavor is pure pref. IPA's are meant to showcase hop profiles, so dont be timid with additions.
an example of my citra single hop IPA
so you can see what I'm talking about.