Some tips:
Part 1: Mysteras Refreshment is HUGE, dont underestimate the additional power you get from actually having mana when you trigger Spirit Sword. Also, more glyphs is a good prep, as it helps you manage the thresholds better (you should never trigger two thresholds at once) and with starting LEMMISI, you can easily scum for good glyphs. Additionally, make sure you use LEMMISI (or even better BLUDTOPOWA) to get your first hit on the boss without converting anything.
Part 2: My goto strat was to go Binlor -> TT for PISORF and knockback and might for easy piety farming. Then before you kill popcorn, go TT for learning and later on a ton of reflex/dodge potions (I think I had 4 of both in my winning attempt). Also dont hesitate to spent one reflex/dodge combo on Garbard, it makes a huge difference. Then a PISORF/BLUDTOPOWA combo with maybe one or two levelups in between and he is an easy target.
Part 3: The most important part here is to get to lvl 9/10 before going down. If you are able to do that, you are fine

I never managed to get 3 lifesteal here and instead went for the easier 15% resist + 2 lifesteal, but you seem to have that done too.
Boss: Sadly, you are not even close to the actual challenge. You probably noticed the first phases ability and how PISORF can effectively be used to get rid of the shield, right? Reflex Potions give you two strikes and the shield is not triggered, making it effectively four strikes

I hope these tips help to bring you further, until you have more information
