I'll preface my comments by saying that finish choice is a very personal thing, what one person is comfortable using and living with (in terms of upkeep and periodic maintenance) another would not. And equally the second person's preferred finish will often not suit the first person's.
The surface of the table is roughly 8x4 feet, and I'm worried about being able to get an even coat over the whole thing fast enough if I use a relatively quick drying finish like water- or oil-based poly. I've used water-based poly finish with good results before, but on much smaller projects.
That wouldn't at all be a problem with oil-based poly since used straight from the tin you have, at the very worst, many minutes but in the right conditions up to a half hour or so before it begins to tack up and be awkward to deal with.
It is challenging to get an even result on a surface of this size with a waterbased finish, but it's doable if you use the right techniques. One of the key tips is simply to use a larger applicator! For an 8'x4' table (2.4m x 1.2m) I'd suggest using a full-size roller such as you'd use to paint a wall. Even with a 4" brush, fairly sizeable by the standards of furniture finishing, even an experienced user would struggle to achieve a result as good and it would most certainly take longer.
I don't have a dedicated work room or garage. Whatever finish I use will be applied right in the dining room of our rather small apartment. I'm concerned about dust getting in the finish since I can't control the space well --- there's a cat and husband in the mix who will be tramping back and forth, scattering debris. :)
This sort of situation calls out for a fast-drying finish, which obviously is right in the wheelhouse of waterbased finishes.
But oil-based varnishes can be diluted and applied as wiping varnish and the much thinner coat that results can be dry enough that dust won't stick firmly to it after as little as 30 minutes to an hour, depending on conditions. And be ready for another coat in just a few hours if it's warmish and not humid.
Dust nibs don't have to be a big issue if you are willing to work the surface after it has hardened up (even a very bad case can be completely eradicated) but obviously dust in the finish is best avoided in the first place if possible.
Also because I'll be working inside our home, I'm concerned about noxious fumes while it dries. There's a couple warm days coming up in the forecast so I'll be able to open the windows, but still...
Obviously not an issue if using a waterbased finish.
It is a problem with oil-based finishes regrettably and there's little that can be done to prevent it. Using low-odour solvent is sometimes an option, sometimes called "odourless mineral spirits" they are not truly odourless but have much less smell. But there is plenty of the normal smelly stuff in the varnish itself so it doesn't completely avoid the issue.
I know wax and oil finishes don't last
Very much so. The mixing of the oil with wax actually makes the finish more prone to removal than conventional wax finishes because it makes it softer than the wax already is (pretty darned soft by finish standards).
I've also read that wax and oil don't provide the same level of protection as other kinds of finish,
Yup. I think "not the same level of protection" should probably be read as "virtually no protection" to give the right impression. Even a fully built-up linseed oil finish (seven to a dozen coats of an oil that 'dries' and doesn't stay liquid) is still an order of magnitude less protection than just a couple/three thin coats of poly.
But what you're comfortable with in terms of cleanup of spills and accrual of stains is entirely up to the individual. What it amounts to in practice is having to wipe up spills very quickly (if not immediately) rather than being able to ignore them until the meal is over.
but I'm not exactly sure what that means in terms of consequences for my table
Because you're staining the table, and because you're staining dark in particular, conventional thinking is you need a protective surface finish. Otherwise abrasion direct acts on the wood surface and is going to start to wear away the colour. This is all levels of abrasion, even sleeves rubbing the edges when dining will do it and wiping the table clean will add to it. And with the wood beneath being so much lighter it'll be very evident once it starts. You might be OK with that given the rustic nature of the table, another area where personal standards are the final word.
There's a good chance it will have hot dishes placed on it, as well as the inevitable wine and coffee spills, sticky bits of food, etc.
The highlighted portion is the part that should worry you. Any wax finish is prone to heat damage and beeswax can often soften just from hand warmth, it will actually begin to melt at the sort of temperatures of a hot plate. And just to note, the blended finish you're planning on using will I expect have an even lower melting point than the beeswax alone.
The wine spills may or may not be a major concern. The dark colour of the table will go a long way to hiding those if they do occur and if you wipe up very quickly they can probably be avoided anyway.
reapply it annually
This is just a guess but I'd expect you'd need to reapply the finish more frequently than annually. Every six months might even be conservative.
I should close by admitting to being against wax as a standalone finish on furniture that sees much use, so I might be guilty of an overly conservative position here. I think the best course of action if you plan to go ahead with using the wax blend is to find out practically what it can stand up to — start with an offcut and sand, stain and wax it exactly as you plan to do the table. Now subject it to some realistic usage tests and see how it fares.
