Good review of hang-on power filters is here:
, as well as useful accessories, or more general, including simple corner filter, here http://faq.thekrib.com/
If you have time, check local availability of the filters, compare prices and check reviews for your best choices on the web, quite eye-opening.
I had to buy two filters - and will improve to the third and better one, because I didn't do this in time.
My first filter, DynaFlo10, was too powerful, like hurricane. This can be improved by rubber-banding polywool to flow exit. Positive side - there is place for custom media (see reviews above), negative - active carbon is always present, what can affect aquarium medication in the first week.
The second, Whisper 5-15 (if I remember right), has reasonable flow, but has less space for the custom media, and biobags are quite porous, in case if you will need to remove the treated algae.
Will buy next the AquaClear - more space for a custom media.
All power filters have problem with restarting after power interruption, if water level is below the working element.
Also, the first two filters will overflow (if clogged, for example) inside aquarium, the AquaClear - outside.
All described filters are working very effectively with their original cartridges/bags with activated carbon, all are very quiet.
Some recommend to buy next size of the filters - check aquarium filters reviews at epinions.com.
Can't help with cooling - my tank will go in the basement for the summer. But you can use heat-tolerant fish and plants. Cooling (water- or freon-based) can be very expensive, or may be air conditioning the whole room.
What is WC?