Pandora Tommarow: help a newbie out

So I rent PT and I'm liking the fact that I don't have to wait until I get a better PC to play this thing. If I can figure out the multiplayer and become good enough to just at least SOUND like I know what I'm talking about ("where are you Cogs?" "That room with the green lights!") I'll almost certainly make this a purchase.

My main problem is:

If a spy is anywhere near a merc, it seems like the merc is fucked. I know its not supposed to be like this, the spies arent supposed to be able to ATTACK the mercs head-on...thus I must be doing something wrong.
My problem seems to be that the spies have countless ways of putting mercs out of comission, and I'm getting hit from all directions. Not knowing most of the time why I even died. My vision will suddenly blur, or my character will just fall down or go into a seizure.
Are spies way overpowered, or am I just doing something horribly wrong? From my limited experience it seems like theres no way to defend yourself. Spies will run straight at you through bullets, only to fucking ELBOW you and send you to the ground. What the shit?

Also, does anyone ever at all make use of the "gadgets"? I know people use Mines and nades and stuff, but are things like the Spy Bullet and Spy Trap just a waste of my time?

Lastly, does NOBODY really play? I tried to hop on not an hour ago to get a few rounds in before bed and couldnt find any real games. Everybody was telling me about "tag". Oh, wonderful, how fun! So now instead of simply losing, I get ass-raped by the three spies camping my respawn door.
If its not "tag" its DM, which boggles my fucking mind because WHY ARE YOU PLAYING SPLINTER CELL IN THE FIRST PLACE!

In conclusion, I really, really, really suck ass at this game. If you want to beat up on me (or like, show me the ropes) my Live handle is Cogs of Fate.

- Fate

Someone on Gamefaqs said the same, that mercs dont use the taser or melee attack as much as they should. That's a really good idea.

Problem is I tend to fucing panic when I see a spy. It's easy enough to say "dont let them in close" but that's the only time I ever seem to see them. I'll walk through a door and suddenly he's all over me, jumping from the ceiling or some damn thing.

Do you guys recommend using the alt vision modes a lot? I try to switch to Movement vision as soon as a smoke bomb is thrown, which works about half the time.

Is Warehouse a good level to be learning on? I figured since it was small and not complicated that would be so, but maybe not?

I'll want to get into a CHUD game as soon as possible.

- Fate

Ok so THATS good to know. I figured I was supposed to be constantly scanning each nook, cranny and shadow for telltale signs with my EM vision.

I'll stop playing warehouse for now. It did seem a bit spy-friendly (the first section anyway).

- Fate