1. Yeah it is but most of the boni are "regenerative" or at least way more abundant. For example "The power of adoration". For every 100 mortals that pray to you you get one point. You get 200 points max. That means you can get 200 points for 20000 followers. Each of the 1000 demigods would be able to get their maximum followers and there would be 20 million people continuously praying to demigods. There are roughly 7.3 Billion people on the planet right now. That means there can be ~7280 Million nonbelievers if everyone would get this perk and get their max points. The cube thing is a different story. If everyone would pick it, on average one would get a 1/10 cube or 1 point. Of course the worship thing is alot more popular but overall the cube thing is in my opinion only a good thing if you know exactly how to approach the subject and outspeed the other ones. One needs 2 cubes to get the costs of the perk back meaning there can be 50 people who do not loose points from the perk at max out of 1000 who could apply for it. Or 32 people who get 10 points profit and 2 people who don't loose anything. This being the average of course. Taking the assumption that 1 out of 1000 people gets all the cubes is very unlikely. Of course the other boni are alot smaller but that is because in the demigod cyoa things are limited due to others also trying to get the cubes.
2. Yes they are however the faerie CYOA talks about "build" transfer. A build would be a set of choices. Taking all the cubes is not part of a build since it does not only include choices but also events happening (in your favor) in a fixed way. The CYOA says there will be 1000 other demigods and in the build that you transfer you take for granted that you get all the cubes. The build would be a set of choices where you would choose what you pick and what you would do if you would get x many cubes. The other thing is something i wouldn't call a build, it is a build mixed with a backgrond story (where you grabbed all the cubes). Also the faerie CYOA does not disclose when you get transfered, since it says you get transfered with a build the assumption i would make the assumption that you get transfered with the set of choices but without any actions done that are not neccercarily part of the CYOA.
As i said before its a cyoa i don't particularily care whether you have a build i consider not right or not. I just argue on the internet because i like it and i prefer to provide criticism when it makes sense. We are talking about someone making up a set of rules for a scenario that has nothing to do with anything real. Whether you follow the rules 100% or 99% or 50% doesn't matter to anyone. I consider it not fitting but i don't personally mind what you do with this build. I just want to provide criticism and argue as long as you don't mind and i think i have a point to make.
To turn that thing you made into a build that would be transferable in my mind (again, not that i personally care, i just want to provide criticism) you would have to make a build where you take that choice and get not a single cube. Then you say how you would spend the points if you would get 1-100 cubes. For example "I would spend the next 5 cubes on the Seer of Infinite Perk. The cubes 6-18 go into strenght." and so on. That way the build would no longer take things happening a certain way for granted.