You can open it via your browser by entering the address. You can also download the Gmail app for that. The app will make the work easier for you.
Yes they can. First though to receive calls and not just voicemails you need to have the phone installed from your Gmail account. It is a browser add on app. You will need your Gmail open to hear incoming calls.
Auto login in Gmail is due to the browser. The browser saves the passwords and auto login the next time you open. You can delete password and log out to remove this.
Bookmarks are in a browser's history or data. You need to delete the data of the browser to remove them. Logging out of Gmail will not affect them.
You cannot block sites on Gmail as it is not a browser. You can block sites on browser. Gmail itself is a website running on browser.
You can show Gmail anywhere by moving the browser window. The Gmail is contained within the browser window. Thus moving browser anywhere will move the Gmail.
Gmail can be set as a start up page in browser. You can edit your browser settings to set Gmail as homepage. This allows to see Gmail homepage when you click on browser.
Gmail history can be deleted by deleting the history of browser. The history is not of gmail but browser. Gmail has no history of it's own.
You can add Gmail as your Homepage on browser. This can be changed in the settings of browser. The browser home page is in the settings tab.
The Gmail Notifier is an application that sends alerts when new Gmail messages are received. It displays an icon in the system tray and shows their subjects, senders and snippets, all without having to open a web browser.
There is in some cases, password that remains in Gmail. That means the password is saved in the browser. You need to remove the password and then forget it in browser.
Gmail is not an operating System but a website. It opens up on a Browser in case on PC's. These browser's run on Operating Systems.