Legion's "alpha" test is trucking along. In addition to some numbers tweaks (I'm kind of surprised that they're doing that, given that they still haven't got all the specs available yet - though I think there's only two or three left,) they've added some new loading screens and maps, including the Azeroth map.
The Broken Isles are, as many suspected, roughly between Northrend and the Eastern Kingdoms. In fact, given where they are positioned, you'd think that you would be able to see Highmountain or Stormheim from atop the cliffs of the Howling Fjord.
Granted, these maps are for gameplay and are not accurate representations of the lore-based size of these areas. Indeed, the game-world itself is far smaller than Azeroth is really meant to be - there's no way that seven human kingdoms, not to mention Dwarf, High Elf, and Troll civilizations could all fit on an island the size of Manhattan (which is roughly how big in-game EK and Kalimdor are.)
The Broken Isles appear smaller than Pandaria, though I don't know how they really match up in-game. Certainly the Broken Isles are meant to be significantly smaller, lore-wise - they aren't really a continent so much as truly a group of islands. In fact, it's even possible that the Broken Isles are the same size in lore as they are in-game (though I'd suspect they're actually supposed to be a bit larger.)
In addition to this map, the Suramar Raid - previously referred to as that or "Suramar Palace" has now been renamed The Nighthold. So we've got the Emerald Nightmare and the Nighthold as the two introductory raids - equivalent to Highmaul and Blackrock Foundry (though from what I've seen, I think Nighthold looks way cooler in terms of aesthetics than BRF.)
We can pretty confidently expect that the Tomb of Sargeras will be the final raid of the expansion (unless they pull a Sunwell Plateau on us,) but the real question is whether there will be a middle tier, or if they're going to repeat Warlords' two-tier structure. Given how unpopular said structure was (I think most of us feel like we were cheated out of almost a third of an expansion) I'd hope that Blizzard would have something planned for the middle of Legion, but for now we can only speculate.
As far as I know, questing in Azsuna and Suramar has not yet opened up for testing. At this point, the clock is ticking, so I hope that we'll see that soon. My current estimate for the Legion launch is some time in late June, after the Warcraft movie is released, but if they want to meet that goal, they'll have to get the feature-complete Alpha up and running soon so that they can just work on bug-catching.
Regarding whether it goes Beta - honestly, I think that this really is their Beta test. In the past (particularly Mists,) they've had more testers than they needed, and players (like me, honestly) have come to expect beta invitations as a way to preview the expansion. By labeling it an Alpha, they can sort of justify not sending out a million invites. It's possible that in the last phases they'll open the testing servers up in order to do a stress test, and at that point we might see a much broader blast of invites, but I suspect that we won't see that until the expansion is nearing launch-preparedness.
Patch 7.0 will likely come about a month before the expansion, so we might see that in May. Excitingly, this will apparently allow us to create our Demon Hunter characters and play them through their starting experience. I doubt that we'll be able to get our artifact weapons, but we should be able to play around with them and try them out in Warlords dungeons and raids to get a feel for the new class, meaning that players who wish to switch to Demon Hunters as their mains (or at the very least level them up first) can storm the Broken Isles at the same time as everyone else.