Calcium Reef test
Phosphate Water supply and occasional tank water
Copper Let the LFS
do this test for you (once to make sure there is none).
You don't need a test for Iodine unless you dose it. Ditto for copper.
Have the lfs
test for the the last two. Phosphate from your tap water or food source is a source of food for algae growth.
Get a refractometer to test SG
I use Salifert and LaMott test kits (great color change to indicate the level). I've given up on my Pinpoint pH monitor and I'm now using the API pH, though I'm not sure I trust it. Seachem also makes some decent test multi-kits.