mike-

i would go with the t5 setup if i were you. they will be much brighter than the pc - this is my experience since i have used both for actinic supplimentation.

skimmer is debatable. on that size tank, with frequent small water changes, you would probably be ok without a skimmer if you have some other means of nutrient export. you could convert the emporer filter into a small fuge for chaetomorpha.