Very much a newbie need advice

OK here goes. I started a salt water tank about 5 weeks ago. Purchased a PS-40 power sweep, canister type filter(cant remember the name but the guy at the pet store said it was more than I would need). Metal Halide canopy with the 10k (I think) bulb with the double blue lights(they look like florecent lights) and the two moon potlight things. I got the water tested last week before I put any fish in the tank and the girl at the pet store said everything was perfect except the KH level and she said it was only a touch lower that it should be and should be fine. I bought a hermit crab, a skunk shrimp some little neon purple fish and this fish that kinda looks like a rock that is supposed to be good for cleaning alge. Sorry I can't remember the names of the fish but the girl at the store suggested them to start since they are supposed to be hardy.

I got 1 lb of live rock for each gallon of tank and 3 bags of live sand for the bottom of the tank. This is what I want to know.........

I have a small amount of this brown or rust coloured alge, a little bit of what looks to be very fine green alge that looks like mini sea weed and a BUNCH of this white stuff growing all over the live rock and the hermit crab. The white stuff looks both powdery and kinda like uncooked bread dough at the same time. I have zero of the green slime type alge that others have posted they are getting along the glass and the water is almost perfectly clear. Is this what am I supposed to have as a start and if not what SHOULD it be like????

Also, what should I get as far as coral and plants, I really dont care about the cost I just want it to look nice. I have always wanted a fish tank(saltwater) and this is my very first one so keep that in mind please

Thanks in advance

Nothing at all, the girl at the pet store said to bring in more water this week after the fish had been in the tank for a week so she can test again to see how things are going and she would set me up with stuff then if needed. She also suggested starting to cycle the water with the RO stuff that was sold just down the street at the water depot. She made sure I was not going to use tap water and threatened to slap me if I did

The guy I delt with the first time was one of those looking for max commission type guys and this girl took me aside during the process and told me what to get and what to wait on and seemed to really know her stuff. But then again I know nothing so this is a learning process for me LOL. As you can guess after the innital purchase I have only delt with the girl.

The tank is a 50 gallon tank and the filter is a • RENA® Filstar® xP2

About 1/4 of the tank was changed.....I was not sure how much to take out and at that time I had not found this site yet

Does anyone have any idea what the white stuff may be?? I have been searching and can't seem to find any reference to it.