Motorized research boost is gated by army research so it takes way more to just dig for it than it would take to research and just bypass it. Research bonuses are fair and balanced but they don't give staggering boosts. That being said, the communist and democratic (interventionist/ neutral) trees are very poor in comparison, making it an unilateral decision to just go through the fascist tree.

That is a lot but very vital for the minor countries that employ it. The fascist tree is the best part of the generic focus as it gives 7% recruitable population. There are focuses in custom trees that build 6 factories, that's 6 factories for one focus! I wouldn't call a total of 7 factories spread over 6 focuses 'overpowered', especially if you can get the same bang for your buck by using two custom focuses.

One generic focus builds one factory, except the last Construction focus which builds 2. It's not overpowered at all, it's actually underwhelming considering what the custom focuses give.