Mainly morbid curiosity, but what was Garth yelling at Wayne in the first movie during the rant that was drowned out by a landing plane? I know, Rule of Funny, but maybe someone who reads lips can figure it out.
Either nonsense or something that would have mostly been funny to the actors. Go on Youtube and look up what David Tennant was actually saying when the series required Martha to fast-forward a recording of the Doctor speaking, he basically just spitballed for a bit, mixing up talking about the necessity of rambling and some randomish in-character statements.
Why do so many tropes here talking about what a Jerkass Wayne was being in the first film? he was understandably angry at losing his show and everything going wrong for him - and he didn't walk out on Garth, he was FIRED and couldn't stay on the show. Yet everyone makes his slight jerkassness to Garth (who was being just as much a jerkass to Wayne) and his comment about Ben trying to "poke" Cassandra (which he was completely right about) a massive deal.
He didn't just say that Benjamin was trying to poke Cassandra, he accused them of having actually done so already. Which is pretty jerkass, even though everything else you said is legit.
Because Wayne is ordinarily Fun Personified, a casual and genial loser whose charisma is based on not giving a damn. When he starts lashing out in frustrated anger, it's more alienating than usual because it's so out of character.
I gathered because he wanted them to stop hacking his satellite dish with this music he didn't like.
Granted, it was the "sad" ending (and therefore not real), but if "Mr. Biggg" had no intention of signing Cassandra to a deal, why did he haul ass over to Wayne's house just to shoot her down?
For the Lulz? Or maybe he was hoping she would try to... convince him. Who knows?
It's possible he figured that she could have a future with his company, but it wasn't the right time. May have just been trying to get his foot in the door, or maybe he intended to shoot her down to make her vulnerable, then negotiate favorable terms with her later on.
When they say 'Led Zeppelin didn't always write tunes everyone liked, they left that to the Bee Gees.', who is this a Take That to?
Presumably the Bee Gees, since the attitude seemed to be more about making awesome music for the sake of making awesome music rather than for the sake of being popular. Doing what you thought was best in quality rather than in market appeal.
It's also a very light Take That since everyone generally does like the Bee-Gees even if they're not usually someone's favorite band.