You can possibly skip the cycle if enough cured LR
is added to the tank (I won't even try to guess on the ratio). I really wouldn't suggest this as a way to cycle unless you understand how the cycle works and test the water to make sure there are no spikes. People do use this method to quickly cycle a QT, if it is needed ASAP.
Live rock really means it has the nitrifying bacteria on/in it.
If you are looking to save money on rock, mix base with some LR
. I'm doing 150Lbs of base from marcorocks.com
and about 50-75Lbs of cured LR
in my 125G.
I have seen you post a few times about dumping the tap water, if you feel more comfortable with that go ahead, it will give you some decent practice in PWCs and premixing your water.
Do you already have sand in the tank, or just SW