If you have the room I would suggest a ducted System for better air flow and temperature balance.

(It costed us $6k in oil the first 3 months of winter when we took over the property)The previous owner had the 1st tenant control the thermostat and had been spending over $10k in oil every year.Now, we installed NEST to control the temperature from our phone and have invested in changing the heat to gas.The heater has been on since the temperature has dropped to 40degrees at night.We have set it to 73 degrees.This morning I get a call from my 1st floor tenant that the heater is not working that it is too cold.I contacted my 2nd and 3rd floor tenant and they say it seems cold but they use portable electrical heater in the room to keep them warm.We are planning on renewing the lease and need to raise the rent.

I would worry about going under the sidewalk cuz you might create a pocket that might collapse.If it was me I would take a piece of oil feild pipe and weld a pointy cap on the end, slege it under the dirt sidewalk section, cut the cap off the end, and fish the new waterline through that way you don't risk your sidewalk caving in from the hole you would have dug. saves the sidewalk, time, and money...If you do but a new sewer line in, i would just pull up the sidewalk...

Your contractor should be protecting the curing process from the elements and extreme temperatures as part of their job.

Before we could even get the inspector in, the temperature hit 15 below zero one night after we made the offer, and although the property was winterized I found at least 3 places in the basement where the pipes split that night.  

There were some metal bed frames and staircase railings that needed welding. 

@Dan Edwards  Temperatures here are over 100 in the summer and get down below freezing in the winter. 

But light gauge steel framed homes will withstand fire up to a temperature point, then they simply melt and collapse.  

They all needed a couple of quick spot welds in places and half a can of gloss black spray paint, and they looked and performed like new.

This magical white goo will take the temperature of a roof in AZ from 200+ degrees (summer) down to about ambient air temp or below.