Ive done about 12 hybrid escapes, and they are relatively easy to do. Yes there is a regular 12v battery under the hood which is where you will hookup the bar. Be very careful with how you place the power cables in the A pillar to avoid the curtain airbags.
There is a small fuse panel located in the passengers side left footwell that you can use to get the ignition trigger from.
Also, if you pull the rear cargo carpet you will see one enormous 36v battery compartment. Don't drill anything to the floor.
When installing a justice with the cable exiting on the passenger side, you may want to take the time to rotate the bar 180 and move the take downs and such, to avoid having to extend the cable, as bringing the cable down the passenger side A pillar and running it under the dash to the drivers side grommets in the firewall will show you that the cable will be about 3.5 feet short.
Take your time and do it right. Make sure you use the open grommet in the firewall near the brake pedal. Don't drill into the firewall. It looks tight but you can fish the LB cable and power wire for the switch box together through the hole at a steep upward angle, while someone on the engine side reaches and grabs for it. What I always have done is use a fishing tool (made out of three very long heavy duty zip ties) and fish it from the top behind the ABS module down towards the grommet.
If you run into any problems, let me know!