I've been trying to make some headway in Cyrodill and could do with some advice. I'm playing Xbox One in case it makes any difference.

How do you make progress in the Assault and Support skill trees? I've tried having the skills in my bar when completing normal quests and whilst that helps the individual skill it doesn't move the needle on the skill tree like usual.
I have been doing loads of PvP, taking lots of resources/keeps, getting plenty of kills but still my Alliance War skills have not changed, this is over a long period of time. I've been stuck at lv4 on both Assault and Support for a couple of weeks now.
Is progression just a question of completing PvP quests? I hope not as that would be glacial given the random nature of them (unless you are Aldmeri Dominion it would seem ;D).
Does PvE questing in Cyrodiil help at all?
So far I'm about 100+ hours played in Cyrodill but still only halfway through lv4 support/assault. Pretty sure I'm missing something here, that can't be right.

How do you change home and guest campaigns without it costing a fortune in alliance points? Seems like the only way is not to play for 2 days is that right?

Does anyone have any links for good reference sites for builds and skill loads outs? I could really use some tips. The almost total absence of communication I've experienced in this game really doesn't help at all in this respect.

And finally, I've just noticed the message 'the gate is open' in Cyrodiil for the first time? I presume it means the wall on the outskirts of my home zone, so it's not open until a certain point? Do they need to take the keep nearest to it?

Cheers for the help.