What would be the effect of making Parry mode persistent?

[Baron Saturday]

Been grappling with pros and cons of making Parry mode persistent (as per this thread and the recent persistent combat mode updates) and I've been having trouble figuring all of the ramifications of doing so.

As is, using parry in combat is a giant pain. It doesn't just deactivate on any movement not caused by clicking on a target, but also if someone kills your current target - leaving you wide open to anything else attacking you. It can also take several rounds to reactivate, during which the stuffing is being kicked out of you. I've also noticed that having parry mode ON isn't enough: My character has to be targeting an enemy before the mode kicks in.

So, to the questions!
What are the conditions that parry turns on and off under?
I've noticed sometimes that the mode will reactivate at the beginning of combat with no input from me, for instance.
What criteria must a character meet in order to start attempting to parry attacks?
As far as I can tell the criteria are: Parry mode on, character wielding a melee weapon and targeting an enemy in melee range.
Is there any interplay between being flat-footed/flanked and parry mode?
As I mentioned earlier, it seems that my character has to be actively engaged in melee (i.e., attack symbol showing in upper left corner of screen) before any parry attempts are made. This makes me wonder if parry relies on the character not being flat-footed/otherwise deprived of dex bonus.
If Parry was persistent, would a character be able to parry while moving?
My initial assumption is no, because of my earlier references to a character not parrying while flat-footed/not in combat.
Would Uncanny Dodge (or any other feat that prevents loss of dex bonus to AC or being caught flat-footed) have any effect on how parry functions?
Because seriously, I have no idea.

I summon the spirit of EvilBrage! Oh Malignant One, utter thy dark knowings!