We've had ours for about 20 years now. We don't use it as a daily car but every one of the previous owners did. The last of those used it as her only car for 5 years and she was not mechanically minded in the least. It did very well though did need a fair bit of work when it came to us.
Despite not getting as much use nowadays as it perhaps used to it has done all sorts of journeys from a short local trip to 100 miles on the motorway. It doesn't complain and is actually very competent. Light controls, good visibility and a willing drivetrain all help here.
Though we don't use it in winter it has previously been out in all conditions. The narrow tyres are actually quite good in the snow and the heater is fierce so demisting was not an issue. The front quarterlights can be opened slightly to assist with air flow.
The engine in our car is a 1275cc. I understand the 1098cc is perfectly fine for daily use, and due to the longer stroke (?) actually turns over slightly slower at speed. We've never done anything to the valves in our engine. It used to run on standard unleaded with a shot of Castrol Valvemaster. We now run it on E5 "super" unleaded, still with Valvemaster added.
The parts supply is brilliant as you know. If we need anything we use ESM as it tends to land on the door mat next day. In our limited experience (sample size of one) they're very cheap to run, assuming you can do the majority of the work yourself.
Mechanically speaking, they're simple. I've done the clutch in ours, had the engine out, head off, refurbed the suspension all round plus back axle, brake rebuild etc... if I can do it then you certainly can.
Interior wise I've put Ford Ka seats in ours. The standard items were ok but tended to cause back ache on anything over 40 miles. Personal preference, of course.
Rust is the main issue, as you know. Ours has had a few bits of welding done in our ownership, mainly in the early days, but living in a garage and keeping out of bad weather means it stays in good shape. As others have said, pay particular attention to the spring hangers - front and rear, cross member and chassis legs. Be wary of anything covered in underseal.
They're brilliant cars!