Using tap water is always a bad idea for saltwater, use Reverse Osmosis / Deionized water or get premixed saltwater from your LFS
. And trust me this hobby is very difficult at times and costly to "start up" so to speak, but can and is very rewarding in the end.
I have lost a total of 3 clowns and 1 lawnmower blenny so far in my 5 months of being in this hobby( not to mention 6 green chromis) due to what I believe was my former LFS
trying to just make a buck. And in these economical times who could blame them. That is why this fourm is so great.
Saltwater tanks can take up to 8 months to fully cycle, not saying yours hasn't yet but it just takes time.
And with your clown issue, did you have them all in at the same time? Because in my research I've read that keeping more than a pair of clowns is not good in a small tank. And finally, I personally have had trouble with damsel's harassing my clowns, and would advise steering clear of damsels, they are awesome to look at but can be very territory based creatures.
P.S. please don't take offense to this, just keep at it and use this forum, its helped me and definitely will help you!