use iso 400. saver for weddings and usually weddings how big do they want to enlarge it? so grain not much problem.
for flash, if u are outdoors or in the day, don't worry about washed-out white faces. hardly happens. try to direct flash or bounce. but if u bounce, maybe u might want to do manual metering, 1/30 s, and about f 4
i'm sure u know this but check the ceiling if u want to bounce. and yes best is practise bounce at home. check distance from subject, vary that as well as degree of tilt.
some simple rule of thumb for non-daring photographers, ie non experts, if u shoot close up, go for direct flash, if wide angle, include like group, can try slight bounce with cardboard attached using velcro.
if u want to do dinners, manual metering, won't go wrong, open up f-stop, set 1/30s and direct flash. don't want to play with bouncing cuz these diners pay with huge angbaos money so want their big face to appear.. cannot take risk. look ugly never mind as long as they appear...
however for day shoot or wedding shoot, u got a lot to choose from so can expt slightly.
good luck. i had fun... hope u have..