Each tap water is different.
It depends on your location. no simple answer for it.
it works for someone, no guarantee it would work for you.
RO + remineralizer is simpler solution, it works for everybody.
Cost wise, no bigger difference, as most serious breeder purchase RO unit to make their own RO water.
It support any standard external flashlight.
Don't worry about TTL mode, I only use manual mode to control the output power.
the problem of 60mm is working distance.
You only have 3 1/2" from shrimp to front of your lens.
Canon 100mm gives you 6" working distance.
My 200mm Nikkor gives me 10.2" of working distance.
for wireless flash trigger, you can't find anything cheaper than this one. works great for me.
You just need find the Canon version.
http://www.amazon.com/gp/product/B00EK5NEQ8?psc=1&redirect=true&ref_=oh_aui_search_detailpage
I use 200mm/F4 Nikkor Micro lens.
the focus length determines your working distance.
the longer the focus length, the greater working distance you get. it's very important.
So personally i will suggest 100mm/F2.8 as standard shrimp macro lens.
We are not scientist, just hobbyist and breeder.
so for cheap shrimp, I use DIY solution, just keep Ca:Mg to 4:1 ratio. with all the success.
for expensive shrimp, I use commercial product, as SaltyShrimp Bee GH+, I keep all my bee shrimp with RO water and remineralize by SS GH+.