While I like it as a site, I also really dislike sites like bicyclerollingresistance…
I liken it to going back in time and showing a savannah prairie-man fire. You’ve shown them something advanced and useful knowledge, but if you’ve not taught them that the dry grass they live in is flammable they’re likely to burn down everything with that knowledge.
That site is an interesting start, but it’s also completely misleading at the same time.
Their testing method is so specific as to be mostly redundant for any of our uses.
They test only on a completely smooth surface. Their results are, therefore, only relevant to a completely smooth surface.
If you’re looking for what tyre you should use as a track tyre on a carefully maintained surface then you can go by their results.
The issue comes that there is more to what creates rolling resistance than simply how a tyre behaves on a completely smooth surface. As soon as you introduce any break-up into the surface then the tyre behaviour can change.
I’m going to cull here as I could rant on that site and the thought process it tends to provoke for hours.
Basically, look at that site as a point of interest, but absolutely don’t use it as the final point of any decision-making process.
As for the rest of your question, personally I think tubeless is worth it, you’re less likely to get a flat in the first place and you will reduce your rolling resistance (over butyl inner tubes) a little also (though latex inners still tend to be faster than tubeless with sealant).
You can just carry an inner tube with you so if you get a flat that won’t re-seal you pop an inner-tube in for the rest of the ride and fix it when you get home.