Couple of quick notes.  I don't think you should have put livestock in the tank yet.  Normally you want to put the liverock in the tank and let it cycle (testing for ammonia, nitrite and nitrates).  Normally after you put the rock in you can start adding critters after about a month or two.  If the rock you got was fully cured it may not be an issue, but if you have some die off on the rock you could wipe out the fish and clean up crew. 

I personally like to run a skimmer from day one, so I would say run the skimmer.  You will find differences of opinions on this, so unfortunately many times this is just one where you have to figure out which way you would rather go.

There is no problem mixing the different types of rock, but again if you put in "fresh" uncured rock into the tank there is a good chance you will spike your ammonia and/or nitrite levels and put the fish and other livestock in jeopardy.

As your tank matures it will go through different phases.  More than likely you will start to see algae grow on both the rock and glass once the nutrient levels start to build up some.

HTH,

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Keith

"Simply put, you believe that things or people make you unhappy, but this is not accurate. You make yourself unhappy." Wayne Dyer

Not knowing something is usually a milestone on the way to knowledge.

Sure he just made a sale.  When I actually worked in pet stores people were amazed when I would say "no don't add any fish".  They thought I would try to push things on them.  I never have felt comfortable doing something like that and never would.  Although some would get upset and tell me they know what they are doing, most were happy that I didn't push the sale on them and they would happly come back later for fish when the tank was ready.

I also am not a huge fan of damsels.  Yes they are somewhat hardy, but they become aggressive and many times will kill or pester new fish when they are added to the tank.  You may consider getting rid of them before the tank has more rock and it is harder to catch them.

If the rock he sold you was fully cured, you may never see a "true cycle" as the ammonia and nitrite are broken down quickly because you have seed the tank with good bacteria (from the rock) and there is no die off on the rock polluting the water.  If you add the other rock you are talking about and it is not fully cured, you may see some spikes in the ammonia and nitrite at that point.

Have you tested for ammonia, nitrite or nitrate at this point?

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Keith

"Simply put, you believe that things or people make you unhappy, but this is not accurate. You make yourself unhappy." Wayne Dyer

 Keith is right that you may of not really have had a distinctive cycle process or it happened so fast that you missed it. If there was enough bio filtration within that live rock any ammonia and nitrite would be quickly converted to nitrate. Keep an eye on your nitrate levels and see if you start to get a build up. Your bacterial population will increase as the amount of bio and waste load increase in the tank. Years ago they sold damsels as "starter fish". They were inexpensive so if they died during the cycle process, no big deal. But Keith is right, they can become very territorial and aggressive very quickly. They will go after much bigger and normally more agressive fish when you try to add these fish to your tank. It's definately better to catch and remove them now than to wait till later.

Tom

Not knowing something is usually a milestone on the way to knowledge.

                                                                                  thanks