Well Im trying to get Vic out of Metzger's hands, I already gave him the radio but Metzger is now asking for 1000$ for Vic, I dont have that amount of money and I really dont want to spend much time trying to get it so I think I'll go killer mode and try to kill Metzger
Im locked with Sulik and the slavers of the first room and my plan is to kill them and then shoot Metzger and the other slavers through the window.
I have like 50 .10 bullets, 5 stimpaks, leather armor, a shotgun with 14 shots and a FAL with 20 shots and Im level 5
Should I do it? Or should go around and do some other stuff before trying to kill Metzger?

You should kill Metzger (1000+ xp) after you've completed the Vault City/Gecko block or have gotten the Power Armor. It's entirely possible to kill him when you're in the Den but it's extremely difficult if you choose the last option. If you have chosen the last option, make sure that you have stolen Metzger's shotgun and his allies' stimpacks, ammo, etc. Let Sulik strike with the sledgehammer and let Vic have the pipe rifle or 10mm Pistol. Arm yourself with the .44 Magnum (if you have it) as well as Metzger's Shotgun. Keep on aiming at the eyes or at the hands or even the legs.

If you have completed Vault City / Gecko and still haven't gotten the Power Armor, this fight will be quite easy. Give Sulik the sledgehammer and give Vic and Cassidy Combat Shotguns. Arm yourself with that arm as well. Make sure that every member of your team has some type of armor on (make sure that you have combat armor; let the others have metal armor or leather armor mk 2). If you have the Power Armor, you can just go in the compound early on with guns blazing. You might suffer minor damage due to critical hits, but that's about it.

And if you played with a female character, you could buy Vic for half the price..

Early on, if memory serves, I've succeeded by first stuffing metzgers pants with dynamite (sneak/pickpocket) and then going on about it. But it's a hard fight, probably too hard if you don't have a proper good gunner built character.

This helped quite a lot but now I have another problem.

I killed all the slavers including Metzger, after that I freed the slaves and then went to the bar for the 1000$ prize. When I went back to the Slaver's Guild Vic want there, I dont know where he can be, I have looked for him all over The Den and I cant find him. Help? I cant reload because I saved before knowing that Vic was missing

Look at Mom's Diner (Den, east side)!

Also, keep multiple saves as you play.. don't use only one save slot! This applies to every game, not only Fallout. ;-)

I set an explosive and ran. Time it right you can cause a significant amount of damage to nearly all the slavers in Metgzers place. They will then start funneling into wherever you ran for coverrage(usually right out the door or inside one of the rooms. You can start pickin em off without expending too much ammo to do so.

Just take some psycho you take hardly any damage from them