BOOTCAMP, Dual disks and TRIPLE Boot Extended!

I am someone who would post once in many years. But I wanted, First of all, to thank LONER T for his support on many discussions and all of you guys who try to help, I will try to ask some questions that might be useful for someone else in the future.

I have a MBP mid-2012 ( 9,2 ) running on Sierra 10.12.6 and I wanted to Run Win10 on Bootcamp just like how I did with Win7 before….After trying to follow every comment on every guide or video to Install Win10 (USING A BOOTABLE USB DRIVE and Bootcamp “EFI Boot“ ) ...The result is always audio device/internal GPU cannot be correctly identified and the running OS will reboot in case you try to update them or Windows try to look for the drivers online….SO The way the audio worked for me was using the DVD (Bios Legacy??!) with Bootcamp Assistant ..but the only downside is that windows will only detect the Nvidia GPU, the internal GPU is not even detected.

I have a couple of questions here please if you can follow:

1- Can I get my HD4000 detected on Windows? ( I am scared to run stuff on my Discrete GPU because I am a previous owner of the miserable 2008 and 2011 MBP’s )

2- If I am planning on replacing my DVD player with an SSD, Is it recommended that I keep my HDD in its place in order for the SMS and SLI to still function accordingly and avoid damaging the HDD?

3- I understand that I will need the optical drive if I want to resize or update windows, but will it work if I use one of these SATA TO USB adapters?

3- Triple booting after installing the 2nd Drive:

I currently have OSX+WIN on the same drive as I mentioned before and I'm wondering which of the below setups is possible and feasible? How can set up the Triple boot without refit?

DISK 1 DISK 2

a-(OSX+WIN) (Linux)

b-(OSX) (WIN+linux)

4-How can I know if my GPT entries are ok before Installing Ubuntu?