In real life, lots of celebs manage to piss away their money. A-Train has been shown to be a junkie with poor impulse control, so it doesn't surprise me that he would fall into that category.
It's not apparent until you get to know them that the supes are psychopaths, and some are less psycho than others. I'm trying to remember if we have seen Maeve do anything that is outright and unquestionably evil. I can't think of anything off the top. Even leaaving the planeload of people to die can be rationalized as being under duress from Homelander.
I'm sure that the wealth, fame and power might cause some to look the other way to some low-grade crazy. The main classic-comics trope has the main downside of dating a supe being the possibility of villains coming after you, and in the Boysverse, there haven't really been villains till now.
Like others have said, there's no reason to not test non-Aryans since they are going to just get rid of them afterwards.
But what doesn't make much sense to me is, assuming Stormfront has been telling the truth about being Vought's wife why Vought would have given the working version of Compound V to minority kids like A-Train.
There's a reasonable argument that she should have stood up to Homelander, no matter the costs. If Wonder Woman somehow found herself in the same sort of situation with a suddenly-evil-and-cowardly Superman, that's probably what she would have done, even if it meant that Superman killed her. It is probably easier to have that thought if, like Elena, one doesn't realize how much of an actual psychopath Homelander is. Yes, Maeve has said he's a psycho, but tons of Vought conditioning could lead her to think that was an exaggeration. It also probably had Elena was "Brave Maeve" rather than the exact opposite in real-life.
They are both heroes and actors. They are literally filming a movie now, and I believe have done individual movies before.
Classic comics/superhero movies and shows have been all over the map as to whether powers can be inherited and how much. Various takes on Superman's offspring have had his kids having twists on his powers (Superman Returns), his normal powers (Jonathan Kent) or I believe watered down versions of his powers. Black Lightning has a kid whose powers have nothing to do with electricity and another whose electricity powers work a different way than his do. Magneto's kids Quicksilver and the Scarlet Witch didn't get magnetic powers but developed their own powers. Franklin Richards doesn't have stretchy or invisible powers as such, but has, well, all the other powers. I'd bet that there have been examples of powered heroes having kids with absolutely no powers, but I'm blanking on them.
It could be that Stormfront's daughter did have some powers but not the slow aging one. Or it could be that the earlier form of Compound V didn't produce results that could be transmitted to offspring, but the current one does. Or it could be that Vought meddled with Stormfront's kid and Comppound V'ed him and he doesn't have the powers as a simple matter of what he inherited from Homelander.
At the end of the day, the writers can make up whatever rules they want on this and the answer will probably be, "some just do, and some just don't."