My first 5K run...Color me Rad

Okay guys, since my last post about fat running I've maintained (and fallen in love) with C25K.

Tomorrow I start week 5 and it's a little scary because I can just make the runs in week 4 (which total 16 minutes).
I've been running indoors on a treadmill but a few days ago when it was nice out my husband and I went for a run outdoors (he has had lots of running experience as it was his hobby until four years ago when we had our first kid).

Running outdoors was so much more satisfying but it really pointed out that I am soooo out of shape. If my husband wasn't running in front of me keeping our pace I wouldn't have been able to do it, luckily he was and I was able to run to whole 16 minutes (not all at once) and the next day my legs were sore (something that doesn't happen after I use the treadmill).

To encourage me to keep it up my husband and I signed up for a 5K 'Color me Rad' run in our city in July.
What are the chances of me being able to actually run the whole 5K by then?
Should I be running every day in preparation, or every other day as C25K suggests? Should I start running on an indoor track to get a better feel for running than I can on a treadmill? What is the average beginner time for 5K runs (if there is one)?

I will be a slow runner with no experience, what are the rules or etiquette of running in a large group of varying experience? I'm guessing I should stick to the sides of the pack because I will probably be one of the slowest there (don't judge me!). I'm in the second wave of runners. They're not going to hold the third wave back if some runners are just that slow are they? I would die if I held up a whole wave of runners because I couldn't get it done with everyone else! Waves are in 20 min intervals.

This isn't until July, but I'm already kind of terrified of embarrassing myself, thank god my friends and family are running with me, my husband is the only one of us who knows anything about it! Tell me about your first run? Have you ever done a 'Color me Rad' run?