I think having people like Hux as second in command makes perfect sense for someone like Snoke. Sure a more competent underling would mean a stronger First Order, but also a threat to Snokes complete control. The power and efficiency of the FO is completely secondary to Snokes personal power and he will most likely be perfectly willing to sacrifice the former for the latter. It's totalitarianism 101. Hux is not respected, clever or ambitious enough to try to oust Snoke, and if something goes completely wrong and Snokes grip is slipping, he can regain it by sacrificing Hux as a scapegoat.
We see shades of this with Palpatine and Vader, particularly in the Vader comics where Palpatine constantly implies that Vader could replaced at any time, keeping him too busy looking over his shoulder for threats to himself to work against toppling Palpatine. This is also an established authoritarian/totalitarian leadership tactic, to have your underlings competing for your favor so that they won't band together and oust you. Stalin did it, Hitler did it, many mob bosses have operated like that and it's usually how the rule of two ends up working in practice. Just look how the Sidious/Dooku/Ventress/Opress betrayal conga line played out.
Of course, both Palpatine and Snoke ended up having their plans majorly backfire on them. Palpatine probably correctly assumed that Vader didn't have the loyal following to oppose him militarily, nor to retain power had Vader simply murdered him and couldn't fathom Vader turning on him for selfless reasons. Likewise, Snoke underestimated Kylo Rens ability to take control of the first order, and ironically, Kylo seems to do it partly by keeping Hux around. As Hux seems to be utterly despised by the older more experienced commanders, Kylo looks good in comparison and probably scores points by publicly berating him, much in the same way Snoke did.
On a personal note, I love Gleeson's pitch perfect portrayal of Hux. History is full of incompetent toadies like him and I almost wish that ep 9 is nothing but a two hour montage of the little slimy bastard getting repeatedly slapped in the face.
As for the opening phone gag, I think it does exactly what it's supposed to do, reinforcing the establishment of Poe as the smartass, cocky maverick hero archetype and then immediately start tearing it down. Sure, to some that might just mean mood whiplash that takes them out of the seriousness of the moment, but to me it enhances it.
For a more extreme example that managed to deliver some very serious moments amidst a barrage of cheap jokes, look no further than the Deadpool movies that basically live and breathe that set up. Of course, you can always argue that whatever they were going for in TLJ didn't work because of flawed execution, but then we're just talking personal opinion.
Edited by penpenpen