I only installed mine with the existing central locking. However I had to do it twice as I had initially installed it with the unit in the door. This thing turned to grot in a few weeks so I would defo have it seated behind the centre console. For the ground and live power you can take it straight off a fusebox blank so there is no need for inline splicing. For indicators I chock blocked mine in to the hazard switch. If you can cut and solder you should, but it can be awkward around the fusebox.
The wire they give you is no where near long enough, I'm also not sure how a 5 wire actuator could be used if you don't already have a form of central locking.
In regards to the boot unlock, never looked at that lock as I have always had central locking just not remote.
If possible I would opt to fit a mk2 vacuum central locking then fit a 5 wire actuator to the drivers door as this will give you the easiest wiring set up along with having the filler cap lock also.