Greetings Tom, and sorry for the exceedingly late reply to your post!
aFS for Windoze seems to be expanding of late in the direction of 3rd party payware scenery. There is supposed to be a Spitfire add-on, but I have yet to hear any further details other than it's in the works, so-to-speak. I don't know much about the iOS version of aFS; can't be much help there, I'm afraid.
As for Steam, I wholeheartedly agree. Not only have I had similar troubles with Steam and their "support", but I've experienced dismal tech support from the developers who integrate Steam into their games. I simply refuse to buy any sims that require Steam. Simple as that.
I wish I could be more help. Hopefully there will be more activity on the aFS forum in the future.
Warmest Regards,
Buzz