Michael,
suggest staying with your prior recommendation, the newest version doesn't sound kind enough. Always be kind. I'm sure Op's like this don't want to be disowned the rest of their lives...
so here is what I'd tell the op since I do this professionally -- and what I do:
1) I don't go with less than 3 bodies -- 1 in the car or I carry all three - or sometimes take 4. Note - I lost a shutter on one body once half way though and if I only had two bodies I'd be thinking I'm dead if I lose the last body I have during the rest of the shoot...
In fact -- I wonder about pros who only carry two -- are they really pros-- someday they'll lose two -- when the stars line up against them
2) I look at every lens and what would happen if I lost one lens - could I cover with other lenses.
3) Light indoors -- I go with three flash and off-camera flash -- but what happens if the flash you buy fails? The pop-up ain't going to cut it for a wedding
4) for major weddings, I take an experienced pro as my second shooter --who can shoot the entire wedding on their own -- we drive separate routes to avoid any kind of chance of a 3 hr traffic jam. If I get sick or in an accident - the wedding is covered
5) both primary and secondary shooters must have insurance and errors and exclusions and businesses.
6) We shoot long and short all day long with multiple bodies in case we lose a card, we have the long and short shots of the same scene. We use only sandisk and haven't lost a card yet ...
7) I take my cards and put them in think tank pocket rocket before leaving the venue in case we get robbed -- they can get the cameras -- but the cards are in our pockets
8) plenty of batteries so as to never lose energy
9) every couple has been happy.
so op - at least get back-up - a rebel with a 18-55 IS and a 50 f1.8. and at least carry two external flashes -- plenty of cards, plenty of batteries.
think fast enough shutter speed as your primary objective to avoid motion blur and handshake
outside in good light - you can shoot AV and get enough ss
inside - think manual and shooting at least ss 1/125 for pedestrain motion
if dancing -- go ss 1/160 or 1/200
ok -- you can get some snaps with this advice. Practice. Good luck!
In the past, I advised every poster to do the same... get backup gear. Is it sound advise? Sure. Is it essential for the non-professional? I no longer think so.
I realized that I've been trying to impose professional standards upon amateur photographers. As a professional, I carry multiple complete sets -- including lenses, flashes, bodies, and batteries -- to any given wedding. But that's what I'm being paid to do.
There are many reasons to expect better results from an experienced and professional wedding photographer. One is -- duh -- he is experienced. He is not only an expert at photography but at weddings, too, which means he not only knows HOW to get the shot, but WHAT the shot is he actually needs to get in the first place. (Ever see a newbie try and photograph a wedding? They often do not even know what they are supposed to be looking for, much less how to capture it if they did.) The couple PAYS for that experience and expertise. Just as they pay for all the extra gear that photographer relies upon for any contingency.
The OP is a self-professed hobbyist with no experience as a wedding photographer. He just wants help getting the best shots possible. There's no indication that he's going to do this professional in this or at any future time. He doesn't need to put any money into this thing unnecessarily. The couple is taking their risks with him, but it is THEIR risk.
The most I could recommend to this OP about backup gear is that maybe he should ask the couple if they themselves have a cheap little point-and-shoot that he could hold onto "just in case". If that doesn't make the couple nervous, then I'd say they know what they're getting into. If it does, then they have time to consider paying someone to help insure better results.
family reputation is at stake. Beg, borrow --but don't go into this without backup gear.
Not only family reputation - but how would the shooter feel if the 30d went out?