i suggest attending one or 2 more weddings (as a backup) before your "promotion".. you r one brave guy..
don't forget.. bring enuf CF for backup.. my "si fu" recommend afew 4 or 8GB so you'll have backup.. one big storage will have problem once your card "kaput"..
seriously jpg will do.. i don't think the wedding couple really mind.. (since they have confidence with you.. *pulling your leg) remember they trusted their big day in your hands..
i have so far gone with 17-55mm with my D300s and may i introduce the nissin 866 (cheaper option). i also have a backup battery pack for my flash for quicker recharging, which i eventually find it quite redundent.. and batteries!! for your cam, your flash.. (i have 14 AA now.. wondering how to utilise them later)
i'd say even a 18-105mm will be good for the whole day.. in broad day light you can use the whole range.. indoors try to limit to 55mm so you can throw the flash light up (still trying to master this).. anything beyond 55mm is like PNS... because you need to literally point the flash right at the subject.. and blast!!
which leads to the next one.. what are you gonna do with so much equipment after the wedding?? *i'll be glad to consider your SB900
i'm waiting for my gary fong collapsible to arrive to try my hand on a few more before the actually one in dec 09.. i really like the diffuser effect..
remember.. advise is advise.. need practice.. and practise and practise.. share your experience after.. and good luck..