Finances are now in order and I have now learned how to properly manage an investment property.

LOL.. most investors probably would not have bought there because the returns would have looked to low compared to other markets in the country... but as you point out you mitigate risk with the proper property to start.Much like what happened in the Portland market.. not a hot bed for most investors to buy rentals other than savvy locals or CA folks. 

Does anyone know if installing separate water meters is a good thing to do in a multi family home?

Yes, I have installed dehumidifiers in a few units (standalone units).  

I know this is properly one of those "what a newbi question" but here goes.

Is there a good authority website that allows you to properly estimate appreciation over say, a 5 year period in a specific zip code? 

pumping a tank should always be on the shoulders of landlord / property management and priced in with the cost of rent also you should make a note that tenants are NOT to use bleach and or antibacterial soaps as these products will kill the bacteria in the tank and cause a lot of problems down the road also it is a good idea to add  a bacteria of some sort to keep it working properly you can buy the over the counter stuff or just add some yeast mixed with water once a year or so I use bakers yeast every three to four years  

(Old 1960s duplex)Any suggestions on this installation?

Probably be a good idea to make sure you know how to fill it out properly.

How can I incorporate a proper value - say the latest real estate appraisal- into the balance sheet for each property?