Inspiron hd partitions and user ac

My plan is to partition my 1TB hd as below

100 GB win 10 os

200 GB programs

200 GB videos

150 GB docs

150 GB photos

150 GB music

50 GB miscellaneous

Is 100 GB enough or too much for the os? Non win programs will be installed in programs drive.

Better ways in organising the hd?

Plan to.create.accounts for my family members. Which is the best way to do this? Read write access for each user, each folder?

Main criteria are to stop them from dowoading files without my knowledge. And also limiting their access to my folders.

Thanks.