I have literally just set one up myself today.
I'm using a trial at www.zenfolio.com
My site is here for you to take a look at. www.chrisburns.zenfolio.com
It does everything you have asked for.
you can lock folders and images for specific wedding or contract work so only someone with a password can access it and they do all of the sales stuff for you as well for a fee of course.
there is no harm in trying it out like I am for 14 days to see if you like it.
the full package which is what you will need to sell your work will set you back $100 US dollars per year which is currently £60 UK
which isnt too bad for what they are offering.
They also do all of the watermarking and loads more .