Ruth
I can't see the images you posted in the word document, but below are some general thoughts.
I know this isn't the core of your question. However, if you are ever looking at new computer options, I recently wrote an article on computers for image processing, which can be found in the Our Articles section of the website. This is more oriented towards Microsoft users, but you might find something helpful there if you are in the market for a new computer.
There is no reason why you can't store all your images in stand alone drives or in the cloud, rather than on the internal disk drive of the computer. However, I would strongly recommend that any images you are processing are stored on the internal drive in the computer, at least until you have finished processing them. This is because the computer can read and write information to its internal drive much faster than to external drives, particularly if those drives are only connected through USB. Attempting to process raw files while the computer is reading and writing to a USB drive is a recipe for frustration.
Also you could consider only storing those images you want to keep, particularly when it comes to Raw files. As you note, with modern cameras it is easy to take hundreds of shots in a very short space of time. However, I don't think you need to keep all of those - in fact you might only want to keep a few images from a photo shoot. It is not uncommon to only have one or two really worthwhile shots from a morning out, and there is no point keeping dross, or tens of images which are virtually identical (from shooting a static bird at say 20 frames per second). I think its a really important discipline to be critical of your shots and only keep those that are worthwhile keeping. I have no idea how many thousands and thousands of shots I have taken of birds, but my set of 'keepers' is relatively small and is less than 1 Tb in total (including Raws and JPEGs) - and the last two cameras I have owned produce 30 Mb+ raw files.
Any suitable external hard drive will work as a storage option. I would keep at least two copies of everything you decide to keep. I have a set of images on my internal (2tb) hard drive and three separate USB drives with a backup copy on each. That's probably overkill but I would never trust fewer than two. Hard drives WILL fail at some point, even though modern drives are generally really quite stable, particularly Solid State Drives (SSDs). Another good discipline is to occasionally check the integrity of your main storage drive using disk scanning software (this comes built into Windows, not sure about Mac). This is because if your primary (parent) storage drive becomes corrupted, and then you back that up after the corruption has already occurred, then you will end up with your back up copies also corrupted. If you are really paranoid, you could also consider keeping one of your copies offsite (so you don't lose everthing if your home is destroyed or burgled).
Cloud drives seem quite a safe option but can get expensive if you need a lot of space. I would need a 2Tb iCloud account which is about $15 per month. Bear in mind that if you decide to change suppliers, or delete your account, you will need to safely transfer your files off the cloud, or from one provider to another, which might become painful if you have a lot. Also you need a network connection to access a cloud drive, and you might not have such a thing if you are travelling.
If you ever started with a clean sheet of paper (ie new computer) I think a very good solution is 1) a fast solid state internal hard drive that holds your computer's operating software and your raw processing program (to maximise raw processing speed) 2) a large eg 2Tb second internal hard disk drive as your primary storage for photos (this doesn't need to be super fast, as it is for storage only) and 3) at least two stand-alone copies of your primary disk drive, whether through additional internal hard drives, external USB drives, or a cloud service.
Hope this helps.
Simon