Q:
Infusion Confusion!!
A:
1. Probably, as the new infusions can only go in the new slot which only appears on infused trinkets. Versatile Simple Infusions will still be necessary for the other slots.
2. Probably not – the new infusions appear to be an entirely new type which only go in the agony infusion slot. The old +5’s are omni infusions which go in any slot, so they’re not equal to the new +5’s.
3. No hard limit, but the cost increases exponentially and it’s pretty certain there’ll be a point where increasing AR enough to progress in fractals could cost as much as a legendary.
4. Can’t confirm myself. Current implementation of upgrades would be that the item inside is overwritten. The cost of upgrading an infusion also includes thermocatalytic reagents… well, if you could upgrade just by dropping an equal infusion on the item the game would need new code just to handle that one instance that can happen with 3 equipment slots.