I would first of all urge you to clean up the question quite a bit.
Some things you need to explicitly state :-
a. You haven't shared what kind of raid setup you are having, is this software RAID or a hardware RAID ?
b. You have talked about both ubuntu and Debian in the same breath and question. Could you be explicit in what you want to have ?
c. From your BIOS screenshots, you are not using UEFI and using BIOS only. AFAIK you do not need to need turn on legacy booting.
I would also suggest you to look at https://superuser.com/questions/714856/trying-to-dual-boot-windows-8-1-and-debian-jessie as it is much similar to what you are trying to do, minus the RAID part. although :-
if you are trying to get rid of MS-Windows altogether then it's a different question.
Please clean up the question as much as possible so it's possible to share an answer that would be helpful to all.
Update - How to know if it is a hardware RAID or software/fakraid. See https://help.ubuntu.com/community/FakeRaidHowto and https://serverfault.com/questions/9244/how-do-i-differentiate-fake-raid-from-real-raid to get a better idea of what you need to look for to understand what you have.