Get ready for some learning on this one. Several specific car and Viper issues come to mind that need to be addressed.
The selected Viper 5806v is an alarm system, too. Are you planning on using the Vipers' alarm functions? The Viper uses the DBI communications on its'D2D port exclusively for the bypass module. Are you planning on going D2D? You could aslo go W2W but that entails a lot of extra inter-module wires.
Does the Focus have a Lock/Unlock button in the center stack area? Does the Focus have the Factory Alarm? Does it have a Factory Hood Pin?
Your Focus uses N.C. Door, Trunk and Hood pins. A full feature bypass module makes the install easier by obtaining the door/hood/trunk status off the CAN Bus and supplying it to the Viper in a normal N.O. form.
While the Focus has the 80 Bit PATS system most newer bypass modules use a Cloning operation ( Viper calls it Key2Go ) to create a working bypass module. This typically requires a bypass module Flash device and Dealer access. Some bypass-only modules can be programmed to the car without "Cloning" if you have two working, original factory, non-clone keys. And, of course, if you have those 2 keys, you could buy a blank transponder key, get it cut, program it yourself and use the 556-U Key-In-Box bypass module.
The vehicles main ignition wires aren't the thick wires used in older vehicles. The Vipers thick wires can be directly connected to these thin vehicles wires or you can "gauge them down" to make the wire run and connection easier and neater. I use some high quality 18 gauge wire with similar colors to achieve this.
There are other considerations but for me, I use iDatalink products (ADS-AL-CA) and have the ADS-USB cable and Dealer access to flash the module and use the KLON process to program it to the car. Most all of the connections are at the BCM behind the glovebox. The hardest part there is removing the glove box with its' hidden screws. Watch a YouTube video on this removal procedure if you haven't done it before. This might be possible for you if you wanted to spend the money on an ADS-USB cable and obtain iDatalink WEB site access. Another option would be using a Fortin EVO-ALL. Properly flashed you could run in DBI D2D mode and program it to you Focus yourself if you had those 2 working Factory keys. You could also buy a Fortin FlashLink4 module and do it completely yourself.
The last option would be to get a PATS bypass module like the Fortin EVO-RIDE. It comes already flashed and can be programmed to the vehicle using the 2 working keys previously mentioned. Everything else would have to be hard-wired. The N.C. door pins would be a PITA but if you use the Dome Light and get around its' Fade-Out routine, you're all set. If you wanted to use the actual door pins, get a Omega AU-NCT module to facilitate the process.
Here are some links to the current install guides mentioned above :
Fortin EVO-Ride : https://cdn02.fortin.ca/download/14221/evo-ride_fordfocus2012_d20140325.pdf
Fortin EVO-ALL : https://cdn02.fortin.ca/download/32021/evo-all_ig_reg_bi_for-focus_2012-2015_80bits_b_32021.pdf
iDatalink ADS-AL-CA : https://images.idatalink.com/corporate/Content/Manuals/DL-FM4/DBI-AL(DL)-FM4-EN_20191218.pdf
Omega AU-NCT : https://www.wiresheet.com/v3/install_guides/Accessories/AU-NCT%20-%20Normally%20Closed%20Trigger%20Adaptor.pdf
Soldering is fun!