Can I use dual 4k Dell P2815Q monitors on the Retina MacBook Pro (late 2013) with Yosemite at full resolution? Will this monitor plug-and-play with Yosemite on this MacBook model without having to install Xcode and mess around with creating custom settings?
Can I have two of these plugged into this MacBook and run them both at 4k (at either 30Hz or 60Hz)? - I don't care so much about refresh rates as I do about resolution.  I won't be gaming or watching movies on them.
This model supports a simultaneous maximum resolution up to 2560x1600 on two external displays via Thunderbolt. 

Alternately, it can support a single display up to 2560x1600 via Thunderbolt and a single 1080p display at up to 60 Hz, 3840x2160 at 30 Hz, or 4096x2160 at 24 Hz via HDMI.