I don't think I'd use one as a daily driver but people do.
Frankly they aren't that comfortable in many ways and of course lack many of the creature comforts and safety features we take for granted these days. That said, we did about 1,000 k's around Tasmania earlier in the year in mine and lived to tell the tale. Mind you mine has aircon, a good stereo and an overdrive transmission but I still wouldn't describe it as comfortable to drive longer distances. If you're just tooling around the Novocastrian 'burbs maybe the comfort factor isn't so important.
The great thing about them is that they're pretty simple to work on, unlike even a basic modern car where there's not much point in even opening the bonnet as there's nothing much you can do under there.
On your specific questions:
- No the back seat isn't comfortable and unless the front seat occupants are pretty short there's pretty much no foot room in the back. This is a design feature Ford have stuck to right up to the current generation of Mustangs which also have no room in the back. Front seat passengers have heaps of room though. Tall drivers find it a bit tight in terms of headroom and getting far enough back from the wheel. I just got some seat extenders for mine to shift the driver's seat back 2 inches after our Tas experience (I just scrape the 6 foot/1.8 m mark). That of course will further reduce rear seat room. All of that said, I have had a bride and two bridesmaids in mine but not for very long trips.
- They can be either very reliable or bankruptcy on wheels. Like any car, reliability is function of maintenance/servicing and replacement of parts that just wear out. And a measure of luck. A fifty something year old car can of course present endless potential for having worn out parts. Rust in the shell is the other major consideration. Buy carefully. No rust and all mechanical parts replaced is likely to equal big bucks, particularly at the moment, and in my mind make for too nice a car to use every day, but your call.
- In terms of things to consider, I guess my thoughts are covered above.