Star Trek: Beyond

Starbase Yorktown isn't just on the frontier, it's apparently close enough to multiple recently admitted Federation worlds that they would also serve as a viable base, and was constructed so as to not show favouritism for any of those worlds. So even if it didn't exist, there'd be M-class planets with presumably millions or billions of Federation citizens in the general area - kind of makes sense to have a major Starfleet presence. It's also narratively important because it's where Krall attacks in the third act - the crew do need to have something to stop, and they can hardly stop him destroying the Enterprise at this point.

This said, I'd thought that Krall's supporters were the Franklin crew, and Memory Alpha suggests they either were (like Kalara and Manas, the two that got names) or, in the event of the Swarm drones - the armoured guys, the fleet of pods disrupted by the Beastie Boys - they were Ancient One technology that Krall was using, like that device he wanted to take from Kirk.

Krall's main associates were the other surviving Franklin crew members, prolonged in life and mutated by the same alien technology that had kept him alive. The scene at the end, where Kirk and Commodore Paris were closing the missing-in-action files on the Franklin crew, showed not only Captain Edison (Krall) but also two other Franklin crew members: Jessica Wolff (who is stated on Memory Alpha to have become Kalara, who lured the Enterprise to Altamid) and Anderson Le, who MA lists as becoming Krall's closest associate, Manas.

They're the crews of the other ships he's trapped; the traitor alien's crew, for example. His chief lieutenants are probably those handful of survivors from the Franklin.

-Splitting up the crew seems to help these movies. It makes The Voyage Home work, and to a lesser extent First Contact with the two distinct planet and Enterprise teams. Works well here too, with all of the main cast getting some good moments- the McCoy / Spock pairing was classic in the original Trek, but I can't recall them getting as many good scenes in any of the reboots as they get here. Karl Urban is the highlight of the new cast.

-Yes to new planets and new aliens. The opening scenes on the red-foliage planet were my favorite part of Into Darkness, but it went downhill when it became a stale retread of Khan. IMDb says this is the first Trek film to not show or even mention Klingons. Don't get me wrong, I like Klingons and I like Worf (some of my best friends are Klingons!) but I enjoyed that they made use of a movie-size budget to take us somewhere a little novel, and even have some non-humanoid aliens in the opening. 

-I walked out feeling a little confused about Krall's motivation, but I feel more reasonable about it on reflection. I recall hearing a rumor about an early draft of Insurrection that centered on a Starfleet admiral or captain going kind of Colonel Kurtz out on the frontier, and I'm curious how similar that would have come off relative to Idris Elba here. Though it all still leaves the question of why whatever aliens made the weapon beamed it into space instead of destroying it.

-On the negative side, a couple of fight scenes during the boarding of the ship were kind of muddled- low lighting and rapid cuts made it hard to follow. This bothered me in Nemesis and Into Darkness, and I was worried it would become a repeated thing here. Lin mostly avoided it, though. Kind of rolled my eyes at the Beastie Boys bit. It's not that I hate fun, but the best Trek has a way of feeling timeless. Pop culture references can have a way of making it feel dated, and you don't want to wind up looking like Joe Piscopo in "The Outrageous Okona".