How are sniper teams used in actual battle operations? What targets are they assigned? How often and when are they used? What do they do most of the time?
I like this question - I worked as a sniper for a fair while. I assume you're talking about the conventional two-person fixed team, so I'll talk a bit about that.
A sniper team, as you probably know, is composed of two people; a marksman who is armed with a sniper rifle (in my day an L42, nowadays they have fancier, more modern things) and a spotter who carries a scope and an LMG. The marksman is generally senior; not neccessarily (especially in special forces where rank doesn't seem to exist) in rank but his job is to take decisions for the team as a whole. Often these will swap over once in position to avoid eye fatuige.
You get two broad roles for a sniper team. There's anti-personnel or AP, which is the one you see in movies and involves shooting people, and anti-material or AM which is the one they never seem to put on TV but is (in my view) massively more satisfying. AM means that you might target radio systems, RADAR dishes, or the engine of a vehicle (or in one case, the propellors of a squadron of aircraft) with a view to take out the enemy's equipment. In a traditional mission, AP will involve shooting a person, probably a set character, for example the commander of the enemy in the region.
The traditional mission and the one you see in special forces units is that a team goes out, lays-up and then shoots the target either on command or when seen. Often what actually happens is that eight people end up going and laying up, so that if there's enemy contact on the way they can take it and don't get killed, and if there are more than two snipers in the team then they'll rotate duties. You can be in LUP for about a month, eating cold rations, lighting no fires to avoid being seen from the smoke, bagging up body waste - it's not exactly as much fun as the films make out. Once you've shot whatever you've got to shoot, you have to work out whether they've noticed you. If not, it isn't unknown for people to just shoot the rest of a particularly thick enemy unit but you're supposed to escape and evade the enemy back to a designated place where you will hopefully be exfiltrated. Of course, while in the LUP you're also reconning the enemy position and gathering intelligence, which can on occasion be the whole point of the mission.
Nowadays, particularly in FIBUA which you get in Afghanistan, they've started deploying teams to cover advancing conventional units, so one team sitting on a roof might cover a section of men on the ground. Their job then becomes to shoot anyone - heavy weapons operators, other snipers - that might pose a problem for the advancing unit. This job is apparently a lot more fun than the other sorts.
Which superiors - military or political - do you trust to only fight a war where it is justified? What makes you trust them so?
In general, if HMQ has sanctioned it that means it's at least checked enough so that squaddies can't be expected to understand the legal business and therefore won't get in serious trouble if it turns out that it wasn't legal, and I don't think that her majesty would tell people to go off to somewhere dusty and kill people if it wasn't worth doing. That's why we have a Queen.
You seem big on the honour system of Britain - do you think that countries honouring old treaties is always a good thing? I just wonder if millions of lives could have been spared if some leaders swallowed their pride.
Really old treaties are just silly to follow, but as a country people need to be able to trust that we do what we say.