There is a Windows 7 (I'm using Win 7, have no idea if its the same about 8 or 8.1 etc.) function which you can Run called "
netplwiz". Click the "
Run..." and type netplwiz. There, you can add new Windows user accounts and also
uncheck the "Users Must Enter A User Name And Password To Use This Computer check box". The next time you log in Windows, you'll not be asked which user account you wish to log in.

Easy part over...
My logic (!)

:
In the User Accounts > Advanced > Advanced (Advanced user management), it will open the
Iusermgr windows, and there, click on the
Users menu-item. There, you will see all the user accounts. Right-Clicking on any user account, and opening the
Properties, you can disable/enable any user account. I think that you can (programmatically) disable all other accounts and only enable a particular account through a variable each time, and that way you can open that user account the next time the PC boots. Programatically of course roll through all your user accounts one by one when the PC boots, so that the PC boots into the next user account (mentioned in a separate batch file, and using the variable set above, or whatever other way) when it reboots and then goes through your complete do-list. Be very careful about writing (and testing, re-testing) such a program or there will be a huge auto-mess which will be hard to correct later.
P.S.:
May be, if this is workable, then you can find a Windows programmer who can write the code for you by advertising in our Hire A Freelancer section... During the tests, don't use the program on ebay, but use/test on another
disposable but similar site.
HTH
