I don't know if it would help to think of the Chromebook as a computer, part of whose 'brain' (the hard drive where long term storage takes place) is in Google's cloud on the internet. Therefore, the only way for the Chromebook to work properly is for the Chrome browser to contact your reserved storage space in the Google cloud. (This is not strictly true, the Chromebook can work ofline but you need to download what you want to work on before going offline.) Chromebook requires you to contact Google, either by logging in and via any of the apps you download from the Playstore.
You will be able to read Microsoft documents but not write them using Word, Google provides alternative apps that will save docoments in a format that Word can read. You can save documents and photos on an external drive if you want but Google provides a certain amount of cloud storage free for the first 2 years, after that you will have to pay for it.
If I were you, I would take it one step at a time, decide which activity you want to carry out on the Chromebook (such as set up your calendar) and Google it, then follow the instructions. There is always help.
The Chromebook is a simple system but the way it works is different to Windows. You will never have to worry about antivirus and updates, Google takes care of that. I hope you soon get used to it.
