We recently played this in our game round, and after trying to grasp the horribly translated German rules, we had two major gripes with the game that I'm not sure whether they were due to our poor understanding of the rules, or due to odd game mechanics indeed...

First, two things that annoyed us before we even started:

• First off, we had trouble with all the special rules (of which most just apply to one or two characters) being in just one rule book. That's easily alleviated with cheat sheets that are available on the Geek, but it's not something that the designers should have overlooked so badly.
• The German rules are severely lacking. Now, I wouldn't have bought the game in German in the first place, but my friend did, and there were text boxes where the text didn't fit in and was just cut off mid-sentence, and other places where stuff was simply translated incorrectly. Looking at the English rules that are available online helped.

But those are easily fixed. Now, game-mechanics-wise, we had three problems:

• There is nothing like a guard order (like Doom has, or Warhammer 40k had 15 years ago already) or similar, so essentially, you can only shoot in your own turn unless you spend one of those oh-so-rare VPs, and it's easily possible for others to come into range, shoot, and go out of range again. If their range is longer than yours, particularly for those attacks that can go around corners, you have a really hard time catching up.
• The rules regarding minimum range do make some sense, in a way, and they help balance the different kinds of weapons. However, together with the line-of-sight mechanics (that are really great, actually), they create odd situations where one miniature can't hit another one at all, because it hides within the first 2 spaces of a room and not everybody has melee weapons or a pistol - and a hand-to-hand attack with the lowest value doesn't necessarily make sense, or even isn't possible because a mini can move 1 less space than required ... stranding with a huge gun at point and not able to shoot because the opponent is then "too close".
• Somebody standing just behind a door required the opponents to basically waste two mini's movement just to get him away there, by first shoving him and then going in with the other to shoot him.

The game really seemed to restrict us in doing the things that would be natural in a situation like the characters were in, like carefully advancing together and laying down covering fire, or waiting with the gun ready for somebody to come through the door, or shooting through the door when you know somebody is standing right behind it. On the other hand, completely unnatural things, like walking into the middle of a room and throwing a hand grenade into the other corner, and then walking back out with two people just standing there, were perfectly possible.

What were we missing?

Houserules.

of which there are 2 I can think of that could help your situation.

1: Bull rush is now part of movement, and uses up 1 movement point to Bull Rush.

2: Shooting at less than minimum range.  Lose 1 die per circle you are below the minimum range for your weapon.

You've already noted it: spend VPs as a means of firing on "overwatch." Not the way I would have made the rules, either.

The game does have quite a cat-and-mouse feel to it, as you move models in and out of rooms to take pot shots while enemy models inside the room say, "Whoa! Where'd that guy come from?! And where'd he go!? I too have found a lot of the tactics of the game to be more about playing the game system than following a more intuitive style of play. Perhaps I play too many minis games, but I too find the gameplay a bit odd. Still fun, but rather odd.