No, LFS is the only private owned saltwater supplier around me, unless i travel 45 mins west on the island lol... which i may have to do now.out of curiousity, is your LFS a petco or petsmart? that could be the root of your advice issues.. unless you get really lucky, most likely just a store employee with basic knowledge.
just stick to what you're doing. get good clean rodi to mix with the salt.. keep your ammonia under control with water changes until your tank bacteria matures.. (that will take about a month). the water changes will also take care of your nitrate issue. whether you can save the guys you have now is a bit of determination and luck.. ammonia will burn the fishes gills and cause other issues - whether they are too far gone or not is a bit of the luck portion.. clowns are pretty hardy (as far as fish go). the nem is a crap shoot.. those guys can be tricky on a good day.
i also wouldnt stress too much about testing other parameters at this time.. as log as you're doing your water changes with RODI (with a TDS of ZERO) - testing with your current kit is all you need. (when that runs out, i would suggest looking for a better set of tests).
phosphates and such will be taken care of with your water changes at this point.. and the guys you have aren't very finicky to phosphates - you would need to test for that if you get into more difficult corals.