Call the city
If its attached to the house, you will likely need a permit
over 2' will require a railing, including the stairs
I do reccommend concrete pilings with a bracket.
Digging a hole and just sinking the 4x4 in is a good idea too,.. but over time the 4x4 will rot and will need to be replaced.
it's easier to just unbolt from a bracket than dig up old concrete
typically that is how you would do fence posts
Before you get holes dug for the pilings, have enmax and atco come out and mark their undeground lines. don't think you would be happy (or alive) if you hit one of those.
If you just place cocrete pads and baseblocks for a "floating" deck, it will shift over time. Perfect for the temporary deck, but at 2' high that requires a railing,.. I would not suggest this route.
I'm' pretty sure there may be some guidelines to these types of decks, call the city and be sure.