There are plenty of DIY for setup online, so buy 1 panel (I assume that's an option) and figure out wiring and such.

Remember if your tenants are paying very high utility bills due to inefficient furnaces, it will put a strain on their ability to pay rent.

I like the double pane ones that Lowes sells, pretty solid value at under $150 per window.  

Probably not- so, it's likely that this will or could lead to, at the very least, a strained relationship with your tenant, which should be fine.

Ditto an ESA damaging the property.But yes, you cannot discriminate against someone with a "dangerous breed" animal, unless it causes you undue strain.

This includes 3 bed bug infestations, 7 gas red tags, a broken window from hell that the first 4 window contractors would not touch and the pane replacement was almost $1k (this window is unique with an absurd fire rating).  

This strains the compressor and can cause it to burn out or wear out premature.

Insulating is a good thing to do in all cases and is low cost.If you need to replace a glass or window, that's the time to upgrade as the marginal addition cost improves the property value - - talking about dual or triple pane retro fit windows here.When restoring after a fire, even though only four windows were blown out, I replace ALL in both units as upgrades and the contractors were already onsite.

There is almost no benefit efficiency wise to new windows, a brand new dual pane window has virtually the same R-value as an old single pane window.

If you say provide and install 15 pieces window $9000, he could give you a single glass pane window when you asked for French window.