Wedding conundrum

I'll get straight to the point.  A co-worker has asked me if I would be interested in photographing his oldest daughters wedding, likely in June.  I haven't agreed to it yet as I wanted to do some homework first since portraiture isn't my strongest area and I've never shot a wedding.  I've worked with this person for almost 10 years and have watched his daughters grow up. Now the oldest is getting married to a young man in the military and they will be stationed in Japan for the next 2 or 3 years shortly after their wedding.  He did tell me that if they couldn't find anyone, that it'd be a "point and shoot" kind of wedding.

He's recently divorced and due to the reasons for the divorce, both he and his ex-wife are struggling financially.  He's offered to pay me and I know if I accept the job and don't ask for payment (given his situation), he'd slip some money to either my wife or myself one way or another.  It's just how he is.  His former mother-in-law recently passed away and she was raising 3 granddaughters with her husband.  Now my co-worker and his ex-wife (who are still on good terms) have stepped up to put their differences aside and are raising these 3 girls in addition to their own children.

Now then.....what would you guys do?  I'm not too concerned about the money aspect, even though a little extra never hurts.  It'd probably only be a couple hundred, if that.  My biggest concern is that I've never shot a wedding and do very little in the way of portraiture.  I just wanted to get some outside opinions if you were in my shoes.

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Life is tough, but it's tougher if you're stupid.
-John Wayne as Sgt. Stryker in Sands Of Iwo Jima