Clarie,
Relax...dun stress. Enjoy ur facial. Ya, must drink a lot H2O. But not too much H2O on the previous night, or else ur eyebags will show on AD. Sleep early, if possible...
Wow string quartet? So romantic... For other songs better to choose ur own, so it'll be personlise. My FH also plan to sing at our 1st march in, but DG say ur sound system not suitable for singing, only good for talking.
All the best to ur wedding day...