I've listened to the Socialist Program for many years now, and I don't agree with your approximation of Brian Becker. He makes many good points and I don't find myself disagreeing with him. I probably listen once a month, so I'm not an expert on his beliefs. I'm also not American.
Of the all the groups in the USA, they seem to be the most well organized and largest compared to FRSO and a better political line than CPUSA/DSA and any other smaller groups. But like I said, this is only what I've observed from afar. I know they had some scandals in the past.
I use Mango. The “premium” version is free with my local library card, it’s like a better version of flash cards. Anki is still pretty good. I used to use Duolingo but since Google bought them they have been evil