>>2686121what I would recommend is looking around for dedicated 35mm scanners rather than a flatbed, that is if you want to continue doing 35mm and not larger formats. they have higher optical resolution (vs. advertised dpi) than flatbeds, though there is the drawback that you have to manually advance the film for each frame.
these guys are a very good resource for scanner reviews, I would recommend the Reflecta 7200 in that price bracket just because I use the newer 10T which is awesome and they are basically the same thing. obviously you can read around their other reviews and see what else is good. I'm not in the UK so I can't comment on availability other than that I searched for the 7200 and couldn't find it so you might have to order from B&H or Adorama, where it's sold under the pacific image primefilm brand. (if they ship to the UK?)
http://www.filmscanner.info/en/ReflectaProScan7200.htmlyour dpi question is better explained by that site, but I wouldn't recommend using a dpi setting above the optical resolution of the scanner unless you downsize the file after. otherwise you're just wasting disk space on extrapolated information.
lots of software does multi-exposures of negatives but I don't find it to be particularly useful. I like vuescan but for whatever reason it doesn't work with the Reflecta/Pacific Image so I use the bundled silverfast.
>>2686125I definitely prefer HP5+ too but it's not like you can't get good prints from T-Max
>tfw you misframe by like 1 degree and don't notice until the print is dry 