USB-C Laptop power and charging

Sorry if this is the wrong forum, I had some difficulty trying to find where I may find this answer. 

We are deploying a new desktop strategy that uses USB-C enabled monitors that will hopefully provide a multi-vendor dock style solution for new PCs. We hope to use the single USB-C/Thunderbolt connector to the monitor to provide Video/Audio, USB Hub and power supply to the laptop. Unfortunately many laptop vendors are being a little unclear on the exact support that is provided/required by these laptops.

Specifically, the new XPS 15 appears to support USB-C charging, but does not say what the minimum USB-PD profile required is. What happens if you plug it into a monitor that supports profile 4 (20v @ 3A i.e. 60W)? Will it work with Profile 5? (20V @ 5A) Does anyone know what profile is supported by the new LG Ultrafine 5K monitor that supports 85W (perhaps profile 5 being 19V @ 5A)?

I have the same questions for the XPS 13, also are there any other options in the range?