Mostly read http://blog.davidelner.com/dual-booting-ubuntu-14-10-on-the-surface-pro-3/.
I couldn't resize the Window partition as much as I wanted (I think I had a pesky "system volume information" that couldn't be moved around). I performed a reinstall and could reduce the partition further.
I've copied the Marvell wifi driver (actually only the usb8801_uapsta.bin
and sd8801_uapsta.bin
were missing on my surface), and indeed the wifi performed much better.
I've copied the X.org configuration (but didn't need to change the kernel as Ubuntu 15.04 has already a 3.19 kernel) and the touch pad works.