I wouldn't worry too much about reputation. Reputation is important if you are applying for high flying city jobs, banking, top law firms and stuff like that. But for the vast majority of graduate jobs they are interested in the fact that you have a degree and your experience on top of that. So don't let the league table placing of the university affect your decision too much.
Hmmm...well if the course looks better at Glasgow, but it's easier to get to Caledonian, that you just need to weigh up whether you can put up with the hassle of commuting over a better course for you. Commuting did my head in after two years so I gave up and moved there, but of course it totally depends on how willing you are to do it.
Doing Psychology and Sociology alongside it might be nice - it will give you a break from the hard science and will develop your essay writing skills alongside your scientific skills. But, if, as you say, you're really only interested in Human Biology, then there's not much point studying Psychology and Sociology if you're not that fussed by it.