What is the besst and leasst expensive way to get to Murano and around Venice. I understand there are many different boats to take you places.
Use the water buses. They all follow a set route just like land buses. The alternative is water taxis and they are expensive.
Be sure you buy a vaporetto pass. You'll save a lot of money.
Locally, the water bus is a "vaporetto". You will using them a lot, so take a look at buying a pass so that you can hop on hop off whenever you want. Writing for the Smithsonian, RS tells you everything you need to know http://www.smithsonianmag.com/specialsections/ricksteves/Getting-Around-Venice-by-Vaporetto.html