Marine Newb

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i am a soon to be newbie myself... from what i can tell (by what i have read, and been told), your hob filter should work for a mech. filter. a protiene skimmer rated for 100 g should be used on your setup. a power head for heavy circulation. live sand for a bed will also do some of its own filtering. live rock at 1 lbs/1 g water will also do its share too. as for adding these two things... at setup, add marine salt to min of 1.023 max of 1.026 s.g. ( hygrometer rquired) do sand upon setup, place a piece of shrimp in tank for about a week to get amonia to spike, once spiked, remove shrimp and let cycle back down to no trace of amonia (test kit required for this part) which should take about another week if not less. once at this point, add cheap fish to maintane a cycle. now the live rock. from what i have understood, only add it at 1 lb at a time (not sure if this is per day, week, or what, but it is too make sure there is not too much filtering and not enough to filter, the live stuff can die with nothing to eat). you could add your desired fish befor or during the lr placement but you may come across fish injuries that way. now lr is a factor depending on the fish you plan to keep... some fish like puffers will destroy the lr as will stars. where fish like clowns will do fine with it and really like anemones placed on it. if you do keep the nicer type fish, janitors...
these guys will save you time and wet arms. crabs, shrimp, snails will help clean sand and rock and minimize algea. if you do the more aggresive fish, you will manually have to maintane the algea, food and fish waste yourself, that is, what your filtering and circulation won't for you... test kits.. aquarium pharmacuticals has a marine kit between $20 and $30 at most lfs that will work fine.

now remember, i am a future newbie and continuing my studies befor i start, i may be off a little on some of this, but this is compiled from hours of reading forums and hiours more talking to marine tank keepers.

study and study more, if you question it, look it up.
good luck!