left 4 dead achievements

I recently realised that there's an achievements thingy in left 4 dead. These achievements are given to you when you do something special, sort of like a quest like that. There are 50 of them, and i've managed to achieve 30 of them(most qte easy one). The other 20 are not easy, and need the team to be well co-ordinated. It's hard to explain without seeing it, so let's just see what they are.

Some of the easy ones which i've done and i'm sure all of you can do:

DRAG AND DROP
Rescue a Survivor from a Smoker's tongue before he takes damage.

PYROTECHNICIAN
Blow up 20 Infected in a single explosion.

TOWERING INFERNO
Light a Tank with a Molotov.

and the list goes on. let's look at the harder ones which i've done(qte proud of some of them).

CLEAN KILL
Shove a Boomer and then kill him without him splashing on anyone.

TANKBUSTERS
Kill a Tank without it dealing any damage to a Survivor.

WITCH HUNTER
Kill a Witch without any Survivor taking damage from her.

BACK 2 HELP
Leave a safe room to save an incapped teammate and bring them back safely.

All 4 Dead
Kill all four Survivors on one life as a Tank.

CR0WND
Kill a Witch with a single headshot.
(This one was damn tyco, did it once and then nvr managed it again)

MAN VS TANK
Single-handedly kill a Tank.
(WOOT)


So if i've already gotten all these y do i still want to play? Why do i want all of you to play and get more pro? cuz 1. it's fun and 2. my friend challenged me to get some of the achievements he has gotten(which i havn't), and i can't do them without a good team. like these...

JUMP SHOT
Headshot a Hunter while he's leaping.
(ok this one not so much abt the team, just need to be abit more tyco. like the one i did to the witch)

AKIMBO ASSASSIN
Survive an entire campaign using only pistols.
(this is what i mean by need a good team)

UNBREAKABLE
Finish a campaign without ever using a first aid kit on yourself.

STOMACH UPSET
All Survivors complete a campaign without being vomited on.

SAFETY FIRST
Play an entire campaign with no Survivors taking friendly fire damage.


And hopefully i can complete some which he hasn't completed yet. like these...

ZOMBICIDAL MANIAC
Survive any campaign on Expert.

UNTOUCHABLES
No Survivors take damage after contacting the rescue vehicle.

WHAT ARE YOU TRYING TO PROVE?
Survive all campaigns on Expert.

NOTHING SPECIAL
Survive a campaign with no Survivors taking damage from Special Infected.

Whee. so wanna play when we have the time? When i come back from prowling arnd the airport. which is some time arnd may. lol sad.