I have no personal experience, if that's what you mean, but taking each of your points in turn:
"Urinating and defecating in full view of male colleagues?"
Why is this any less dignified when it's a man doing so in front of men? People will get used to it.
"Would a female change a tampon in such circumstances?"
Possibly, or they might find a discreet way to do it, or frankly no-one will care because getting shot at is probably a greater problem. Besides which I'm sure people in the army are used to the sight of blood.
"What about the sexual tension during 'down' time on a long range recce patrol of say 3 weeks?"
Might be there, might not be, but again people will get used to it. And it's possible for men and women to spend time together without the "we're so gonna bang" thought hanging around.
"One soldier makes it his duty to look after the female in the patrol, to the point where he loses sight of his obligation to all in it?"
Any women capable of serving in the front line won't need looking after as some sort of dainty Damsel in Distress.
In my opinion (which is perhaps in this case not worth much) many of these things are problems now because the culture of the front line is not used to women. But like so many other things once it opens up the culture will change and most or all of these problems will disappear.