I am revamping my system as I migrate to Win 10

Microsoft encourages us to use our Microsoft account to sign in. I do have such an account because I have an Office 365 account

I have a desktop and two laptops (one is my wife's) on our home network and would prefer, to keep things simple, that we use the same Microsoft email address as a sign in for all 3 machines. Implied here is that the same password would have be used to access the machines and our Microsoft accounts and email. Does this make sense? Will I be lessening our security? My goal is to set things up so that my wife can go to any of the machines and find the same structures and logins

AS I understand things, my Office 365 accounts gives each machine access to their own 1 TB oneDrive account. I would like to keep our computers synched with each other. Due to pictures, ebooks, and music we have almost 1 TB of user data. If I can not reduce the data I would have to use more than one OnEDrive folder to hold it. With three machines and three OneDrive accounts is there a way I can keep all of the data synched?

Please bear with me - both of us are 74 yrs old and not too computer smart

Thanks for your help