The filtration should be strong enough to make a current throughout the tank but not too strong for the species of fish you choose. Most Bettas for example do not really enjoy being thrown around in the flow of the water. Right now, without fish to worry about I don't think the speed is that important.
If you are doing a fish-less cycle you will need to buy some Ammonia (without cleaning solvents, I heard in the US Walmart carries it) and follow the instructions for fish-less cycling. In a fish-in cycling process the ammonia comes from the fish's waste.
Ammonia feeds the bacteria that will convert it into Nitrite, and another type of bacteria needs to build up too convert it into Nitrate.
Ammonia and Nitrite are both toxic, Nitrate is tolerated well as long as it is not allowed to get too high. Live plants will be helpful using up some of these Nitrates.
Once your tank no longer shows any levels of Ammonia or Nitrite, and you have readings of Nitrate your tank is considered cycled. This takes 4 to 6 weeks. It then is safe to add fish. Some only add a few fish at a time, and wait a few weeks before adding any more, while keeping an eye on any Ammonia or Nitrite showing up. By doing water changes you can bring the readings back to safe levels for the fish. Others add the whole stocking at once, since the filter has been conditioned to deal with a large amount of Ammonia.
Once you have a stocked tank, and you decide you want to add any new fish it is wise to put them in a quarantine tank for about 6 weeks. New fish are stressed and more susceptible for infections, and may bring an illness into your tank. This can put your whole community tank at risk. In a QT you can better keep an eye out for any signs of illness and medicate them less costly!
I'm not sure if that clears things up a little better for you. Keep asking questions, it's how we all learn!