to store movies, photos, music and such not on my macbook pro and then access them remotely (like from out of town) without carrying an external HD with me?
You can use a cloud service such as Onedrive, Google Drive, Amazon, Copy, Box or Dropbox etc - most have free allowances enabling you to sign up and try them.
These services require you to keep a copy of the files on your MBP/laptop and enable a backup copy to be kept "in the cloud" as well as being able to sync the files to other devices.
Or you can have your own server at home (say an older Mac-Mini - I use a 2007 model) and keep your files on it as a shared facility - meaning other machines you allow can access them - possible here to only download those files you want when you need them.
BUT the route you desire, where the files are not kept on your MBP/laptop will mean you require access to the remote machine to access any of your files so you WILL need either a cellular data, cable ethernet or WiFi connection to the internet to access your files. Even when you do, don't think you can painlessly download any files you wish, if you want to browse say 50 of your photos you may have quite a wait to do so and it may be quite expensive if done on a cellular connection.
Better to keep a local copy of the files you use most often and need/want to access regularly on the MBP/laptop and keep the seldom-used files on a USB drive at home or carry it with you depending on your needs.
Personally I'm the other way and carry a copy of almost everything I possess (except for my movie collection), so 500GB of photos, another 100GB of music etc, hence I have a 1TB HDD onboard for carrying it, then I use a Mac-Mini at home and iMac at work to sync with and Time Machine backup to. 3 copies in 2(min) different locations 30Km apart for security.