Ahh ok, yes, you can add your rock directly to your tank in this case. As long as the rock is cured from the vendor, then the odor should be minimal. I did the same thing when I 1st set up my tank about a year ago.
I purchased my rock, cured, from a local shop, where he had it running in tanks dedicated for live rock. Even this rock, however, began to smell a little bit after a couple weeks. Nothing overpowering, but just a little sulphur odor noticeable if you sniffed the water.
If your rock is not cured, however, than you can still use it in the main tank as part of your initial cycling, but the odor could be much stronger. As I understand it, curing live rock at home has led to divorce in the past :lol:
I also kept some Astraea & Turbo snails during my tank cycling, as well as a sandsifter starfish. These guys did just fine.
Hope this helps...
Pete