Yarraville is not near the sea at all. I only really know the east side of the bay: St Kilda, Brighton, Hampton, Sandringham, Black Rock, Beaumaris, Mentone, Parkdale, Mordialloc. you can get into the city in 30 mins from these you have to get to Parkdale to buy in the range you're looking at, though you can rent in the pricier areas near the sea, and look about you then. Further down towards Mornington and Mt.Eliza is meant to be very nice.
As for craggy beaches - Australia is very old indeed, worn to the nubbins, and there aren't a lot of dramatic crags/cliffs of any description on the bay, and most of these have the tide permanently up to the base!
In fact, Oz's flatness is one of the first things you notice.
There ARE hills and mountains, just not quite like the ones in Europe/America.
Don't be put off by any of this, it's a great place, And we live by the sea as a priority, so can appreciate why you'd want to do the same.
Lots of good walking, especially in the Dandenongs, where you'll get to see (and hear) that lyrebird that does the chainsaw imitations in the David Attenborough Life of Birds. Try the You Yangs, or Bushranger's Bay, where the rock pools are so deep you can swim in them.
Easy to snorkel - end of the road for me - and quite a lot to see, though the octopuses should not be poked.
Nice place for people with children. I guess you'd make friends through their friends. I didn't find this very easy, as I was in full-time work within six months of getting here. Lots of friendships generated via sports, which is taken loonily seriously here. Surf Life Saving Clubs are very good indeed for getting to know others; I can thoroughly recommend them, and they always want new blood, as it were. (Only occasional sightings of sharks in the bay, always followed around by helicopters and reporters).