Hearthpwn

If you're facing a ton of control warrior on ladder it might make sense, but most of the time ysera is way too slow, and way worse against aggro/shaman. Geddon definitely improves winrates vs. shaman. If you really don't like Geddon which is understandable because it's almost useless when youre ahead, I would highly recommend that you replace it with Bloodmage Thalnos.

Soggoth is a key card in this deck because it helps against matchups like rogue, priest, and control warrior a ton. If you drop him on an empty board against most decks it's usually game over. The first minion that comes to mind is Cairne because of its barnes synergy and stickiness.

would it be worth it to switch an arcane giant out for a moonglade portal for a little bit of extra life gain?

It may be useful in some matchups, but it's your call. Without ancient of war, you don't have any big taunts to heal up which is where Moonglade Portal really shines against control. It would help with Barnes and consistency against aggro however. If you're feeling like you don't have enough life gain, try holding back from using feral rage as removal unless you have no other options. I like to hold on to feral rage for healng or burst late game.