1. Will the "home hub" work with my NAS?
Yes.
2. Can I change the password on it, or otherwise mess with the settings myself or is it locked down and sneaky?
Yes, you can change all the usual settings that might find on a basic home router. You can turn off the wifi sharing but then you get locked out of the free BT Openzone wifi, which seems reasonable. The Home Hub itself doesn't seem to squirt out electrons with the vigour of my previous all-bells-and-whistles Belkin router (and does have external aerials), but it's reasonable enough.
3. What other drawbacks are there to BT Infinity? I'm aware of their less-than-stellar record on customer service, so what has been your experience?
Customer service: shit. They installed one of my extensions on the wrong side of the microfilter. Millions of tortuous calls and emails later, I gave up and put one of the old microfilters back on the extension. They never did close out the support case. That said, the service has been rock solid other than that, and by and large I never need any support.
I'm not too worried about them inspecting my packets, let's face it, given cause there's always a legal provision for obtaining them, and I don't see BT going out of their way and spending money snooping on me. I don't believe in piracy and I'm getting too old for p0rn.
I can't say I've noticed any significant slowdowns in the evenings. I don't do anything that would get throttled, so can't comment on that. I have the unlimited service.
4. Does anyone else use BT with a VPN service? Any problems?
All my work stuff goes via VPN OK. I don't bother for personal stuff.
5. What are my other alternatives for FTTC speeds and a tinfoil hat level of security?
Won't it all be going by BT at some point anyway?