That first pic is good, it's not as easy as i though, was a bit shy getting my camera out in a Medway High Street. Wanted to get some face shots really.
I usually stroll across to Rochester in my lunchbreak but I too always feel a bit awkward snapping people I dont know. Especially with it being hot the last few days - dont want people to think im some sort or perv......

Did you go down into the crypt at the cathedral? I havent tried it, but I reckon bouncing some light off the curved archways with a few off camera flashes could be good.
Also, if you go again, look out for a coffee shop called the Def Cat - they use their wall space for artists wanting to display their work, so there are usually a lot of creative types in there.