do increases to global area of effect (such as from the passive tree) increase the radius of its proliferation?

Yes, such modifiers apply to the area the ailment is spread in.

Because IPS has an AoE tag

No, that is not because of the tag on the gem. The gem has the tag because it applies an area of effect, not the other way around.

SelfReconstruct

Does the consecrated ground effect from Bottled Faith (Consecrated Ground created during Effect applies (7-10)% increased Damage taken to Enemies) stack with Holy Flame totems enchant (Consecrated Ground created with Holy Flame Totem applies 9% increased Damage taken to Enemies) if I stack both of them on top of each other? Or does one override the other?

Something can only be affected by a single area of consecrated ground at a time (the ground doesn't stack). If you create the ground around a totem when not under the effect of the flask, then drink the flask and create a second patch of ground while under it's effect, only one can apply to any given enemy. But if you summon a Holy Flame Totem during the flask's effect, that ground patch is created affected by both modifiers, and will thus apply (16-19)% increased damage taken to enemies in it.