Vader, i am taking my time when i should be sleeping to write this, so i wholeheardly advice you to listen.
You are the manager. You make decisions. Your ass is on the line. You make sure the company succeeds.
Just because you want to be strict it DOES NOT mean you are going to be hated or become and evil manager. I've met plenty of managers who have 0 tolerance to some issues but are great people to work with.
Your workers disrespect you because they feel they as a group have the power to influence you. You are the new guy. They want to take advantage of that and TELL YOU HOW TO DO YOUR JOB. Tell me something, if you had a kid, say 5-6 year old, and he told you. "Buy me this. Buy me that. Play with me right this second.", you wouldnt do it just becuase he said it. So why are you letting these guys affect you.
They can sit in a circle and jerk off all day while talking trash about you, what counts is when work day starts they better be working.
Verbal warning work for 1 may be 2 weeks, then the person realizes they can still get away with what they are doing.. think about it, you are speeding on a road and get pulled over. cop says it is a warning.. you drive again, 10 minutes later you are speeding. Now if you got a ticket, that would be a whole different story
Written warning do their job, unless you go overboard. I dont know if you guys have the 3 written ups policy, but make sure the write up COUNTS. you cant do a "semi-write up" that doesnt count for anything and doesnt change a thing.
**** bro, if anything, give anyone who is giving you advice a call and make them fly in town, we'll fix it for ya
Good luck