Your best bet would be to leave the files on your computer (get a larger drive or install a 2nd drive in it, if need be)...

AND back that up by putting it on something external, like a flash drive or an external drive or "cloud" storage. And I agree with the idea that if you are going to have the backup "on site" with you, double it by having redundant drives you swap out every so often (depending upon how much you shoot, how important your images are, etc.) You might swap them weekly or monthly or every few months. It's up to you. If something happened at your home and you lost BOTH the computer with the primary storage and the external storage device, how many images are you willing to lose irreplaceably?

The software that came with your camera (might need to download and install it) should be able to convert a RAW file to a JPEG easily. Look for something like an "as shot" button, which will use the camera settings recorded in the RAW file and do the conversion based on them. Of course you also could adjust, tweak and modify the RAW file. That's much more possible with the "full data" of the RAW file than it is with in-camera JPEGs.

You may not be aware of it, but you are always shooting RAW files. Every image any digital camera makes is a RAW. When you set the camera to "JPEG", it's quickly converting the RAW file into that JPEG and "throwing away" the original file that contained quite a bit of additional info. To get some idea of the difference, sometime set your camera to shoot RAW + JPEG, take a few shots, then download them to your computer. The two files from each shot will have the same name, but different suffixes when you look at them in your computer's browser. What you'll see is that the RAW file is larger than the JPEG. The difference is what's being thrown away when the camera makes JPEGs.

Besides the RAW always being larger, both RAW and JPEG file sizes vary from shot to shot depending upon how much detail is in each image. An image of a very plain gray area with just a few details would be a lot smaller than a landscape with a lot of trees and foliage details, for example.