Thanks to ammulder's guide, installation was pretty straight forward even for a total newbie like me. It took only 2 hours to install both El Capitan 10.11.5 and Windows 10. However, I was experiencing all sorts of issues other people on this thread have mentioned. sleep/wake, shutdown, bluetooth, audio. duplicate clover entries, etc. I had to spent another 2 days to tackle those issues.
1. shutdown
When I shutdown the computer, it rebooted right away. "shutdown fix" in clover configurator solved this problem.
2. sleep/wake
When put the computer to sleep, it goes to sleep and then about a few seconds later it turns back on automatically. Turning off "wake for lan" didn't help. The link below helped me to identify the wake problem.
http://osxdaily.com/2010/07/17/why-mac-wakes-from-sleep/
It was bluetooth that is waking up the system. I unchecked "Allow bluetooth devices to turn on this computer" on bluetooth preferences, and now sleep/wake works perfectly.
3. audio
front/rear/hdmi audio all works but front/rear audio doesn't work when computer wakes from sleep. I tried CodecCommander.kext and it indeed solved the problem, however the computer wakes immediately after sleep again. I eventually removed CodecCommader.kext and just using hdmi audio for now. sleep/wake is more important than having perfectly working front/rear audio.
4. duplicate clover entry
It was actually much easier to use EasyUEFI to delete duplicate entries and prevent further duplicates than doing it on clover menu manually. On OS X I mounted EFI partition, renamed boot folder to boot.disabled. Rebooted to windows, using EasyUEFI deleted all duplicate entries and entries pointing to boot folder. And I created a new entry pointing to CLOVERX64. No further duplicates now.
5. apple wireless keyboard not connected automatically on windows
I had to keep re-pairing keyboard on OSX and windows back and forth. The link below totally solved the problem.
http://www.tonymacx86.com/threads/d...-trackpad-and-magic-mouse-bluetooth-se.72201/
Thanks again ammulder for putting together an excellent guide here. Cheers!