hi Cathy,
depending on what you plan to keep, i see no reason to keep a canister filter at all. unless you plan on overstocking your tank, the live rock should handle your biological filtration. if you really feel the need to keep one on hand, a magnum 350 is handy because you can alternated between carbon and/or a filter cardridge that can be cleaned and reused.
another consideration maybe the addition of a refugeum. these work great. i had one on my 46 gallon bowfront and it more than handeled my needs. i would on occation run the magnum for carbon, or to 'sparkle' the water
as for protein skimmers. thats more a debate. i really like lifereef equipment for stand alone units for use with a sump. ive never used one of their hang on's so have no experience with them. a lot of people like euroreef, but having not used them i dont know. i have had great luck with CPR backback skimmers, and infact generally ditch the rio pump and just use airstones for my bubble generation.
im sure you'll get plenty of different answers, but if you have questions feel free to ask
HTH
/john