Beginner Gardening: Need to fix this lawn, 2 by JatS

JatS wrote:
Hi everyone

This is my first posting and I was looking for a bunch of help. This is the lawn at my dad's house and he was recently screwed over by his landscaping guys and now refuse to show up and do the work. I won't go into details but sufficient to say I am going to using mine and a bunch of my little cousin/friends to help finish this lawn.

As you can tell this lawn is in rough shape and I only have 30 days to get it in place for a wedding. I am asking the following:

1. What should I use to remove the weeds that won't kill the plants
2. What should I use to make the grass grow back
3. Should I use mulch around the plants that are healthy?
4. Is the lawn too far gone for the time and I should just drop the cash for new grass?