There is a ton of information in the exterior lighting forum.
Debunking popular Internet beliefs, HIDs use a little less power than the factory halogens and have about the same current in-rush at start up albeit for less milliseconds. HIDs also do not run any hotter than halogens, you will not melt your headlamp buckets with a 50 watt HID system.
The headlamps are powered by pulse width modulation, this simply means the power is switched quickly on and off. I have a scope shot of the power feed in in my gallery if you are interested in seeing the durations.
One common issue is light flickering, this is due to the PWM power source turning on and off. Second is a lamp out code when using a wiring harness. The first issue can be removed by using a 4,700 uf capacitor in the headlamp power feed, the capacitor will provide power to the HID ballast during the PWM off period removing the flickering. The second issue can be removed by adding loading resistors to each headlamp (most harnesses include the loading resister) so the BCM sees that the proper amount of current is being used, better yet, don't use a wiring harness.
There are HID kits available that are labeled as "CAN Bus", even through the lamps are not on the vehicle's CAN bus. They simply have incorporated the capacitor in the HID wiring to prevent lamp flickering. Loading resistors are not need and don't use a wiring harness, a harness will force you to use loading resistors and add more points for failure. I've have had a 50 watt, 4,300K HIDs in my Laramie since 6/13 with out issues.
Color temperature is more about what you are trying to achieve, do you want boulevard looks or lighting? If you want to light your way, go with a color temperature of 4,300 (typical OEM) to 5K Kelvin. For the fogs, I would leave them halogen but if you insist on HID, look for a color temperature under 4K Kelvin.
2013 RAM 1500 CC Hemi Laramie 4x4 in Cherry Red
2015 RAM 3500 CC CTD Longhorn 4x4 SRW in Western Brown