External GPU advice

Hi Slackers,

I have been considering getting an external GPU for my laptop due to recently getting re-interested in flight simulators. The laptop is a Thinkpad T430 with Intel HD4000 graphics. My plan is to get probably an Nvidia card connected to a dock compatible with my laptop's ExpressCard slot and a separate power supply. I have a few questions that I'm hoping can be cleared up before I jump in, though.

1. A general question - does anyone have experience with external GPUs in Slackware? Any advice?
2. I will need to install the proprietary Nvidia driver. Can it exist with no issues alongside the Intel driver?
3. Let's say I want to use the Nvidia card. I think I will need to use an external monitor, which is fine. But how do I tell the system to use the external GPU / monitor / driver rather than the integrated graphics and laptop screen? Will it automatically detect it on boot when it is connected, or do I have to manually enable it each time?

Thanks in advance for any advice people can provide.