How do I get my windows/tabs to stay up, the re-open upon the sleeping and login process?

It sounds like your Mac is set to automatically log you out after a period of inactivity.

>System Preferences>Security & Privacy make some changes here

whereas what you want is to just require a password when waking (but remain logged in the whole time so none of your apps quit).

Go to System Preferences > Security & Privacy > Advanced... (you might need to click the Lock icon in the bottom left to enable this button). Make sure you have "Log out after X minutes of inactivity" disabled. Then you can enable "require password [immediately] after sleep or screen saver begins."

macOS Sierra / High Sierra: Require a password after waking your Mac

Try setting up another admin user account to see if the same problem continues. Please post back on whether or not this worked. Also try the Safe Mode. Please post back on whether or not this worked.

Isolating an issue by using another user account

Safe Mode - About

Safe Mode Startup – El Capitan. also Sierra

If it works in the Safe Mode, try running this program when booted normally and then copy and paste the output in a reply. The program was created by Etresoft, a frequent contributor. Please use copy and paste as screen shots can be hard to read. Click “Share Report” button in the toolbar, select “Copy to Clipboard” and then paste into a reply. This will show what is running on your computer. No personal information is shown.

Etrecheck – System Information