Then press the Apply Changes button at the bottom of the page
Absolutely, all of the mobile life and a surprising number of sessile species will move to the lace rock. As far as the algae goes it should be pretty much impossible to tell what was live rock and what was just dry coral or other filler after 3 or 4 months with good water conditions.
If you are going for a reef you can also colonies of critters transplanting them all over the tank . Watch for any infestations of hazardous critters like certain , etc. very closely at this stage because they can colonize your tank very easily to.