1) It's not so much a confidence thing with British guys as it is an expectation of being gentlemanly. That means being humble as well as being smart, funny, etc. (There are always exceptions, but those are usually overconfident dicks)
2) The whole compliments thing depends entirely on the guy you're talking to. It's either gentlemanly, charmingly humerous, or just rude. There's a thin line between the last two.
3) The reservation you see tends to be out of respect more than shyness, but again, there are always exceptions.
4) Yep, the accent's a thing.
5) Yeah, pretty much. Don't go to Liverpool expecting to hear people talk like Daniel Radcliffe.
6) Not true at all. We buy canned food for the most part either to save money as students, or for long term storage. But you'll find lots of guys willing and able to cook.
7) Sunday roast is love. Sunday roast is life. (Seriously, don't fuck with our sunday roast. We will end you.)
8 ) "I'll put the kettle on" is equivalent to "Let's talk through your problems for 4 hours and I'll try to make you feel better".
9) Totally depends on the guy, though I've not dated anyone in my life who was so obsessed with football that it negatively impacted their life.