Ok. As far as test kits I would say depending on what your going to do with the tank really depends on the kits you have.
Are you looking to only keep fish? Are you looking to go into coral keeping?
If your doing a FO
tank then the kits I would say you should not be without would be Ammonia, Nitrite, Nitrate, PH, Temperature, and Salinity.
If your doing corals then add to the above list Alkinity, and Calcium.
Its a general suggestion to not add any additives you dont test for. So if your adding a calcium additive you should have a calcium test to make sure your either adding enough or even need to add any at a given timeframe.
The crab will probably be fine. One thing to watch is the snails. Snails are rather sensitive to salinity changes and if the LFS
keeps their tanks at a lower salinity (they probably do) then shocking them to a higher salinity to quickly could damange their internal organs. Keep an eye on them for the next week. Sometimes the effects are not quickly seen.
What I like to do is float for 15 - 20 min in bag with your tank lights off. Then open bag and continue to float. Add 1 dixe cup of tank water every 5-10 min until bag is full. Pour out 1/2 of bag into bucket (dont use sink just in case something finds its way out) then repeat the above till bag is full again. Then remove all water from bag and place items into tank.
Another method is to use a drip line. You would put what ever you got in a bucket with the water from the LFS
after floating. Then you would use an airline tube with a knot tied in the middle to control the drip rate. Drip approx 1 drop per sec for 40min or so then introduce your items to your tank.
The hermits will find enough to eat off the live rock I suspect. The snails will find food but if your really worried you could put a small square of dried seaweed in the tank.
I would suggest your next purchase be a good marine book or two. Im not trying to keep you from asking questions. That would never be my goal. What I want is for you to have a reference when either you cant get to this site or you need to just reference something real quick. If you have not yet seen our Aquatic Library you can find it off the homepage on the left.
Two books I like for beginners are The New Marine Aquarium and The Concientious Marine Aquarists. With my favor going toward the last.
I personally would bump your temperature up to 80F I keep my tanks at 82F usually. These temperatures are closer to the natural average temp on a tropical reef.
If you have not done so yet get some buckets or a large plastic trash can. YOu can use this to mix up your fresh saltwater from now on. The only time you should add salt to your main tank is the first time you fill it. This is because undisolved salt and burn your fish and inverts. Plus there is a lot of change going on within the first hours of adding salt because there are many other elements other than salt in the mix and they are all mixing together and having chemical reactions.
BTW, did you ever say how big your tank was?