[cypher]

The second link is a treat rather than a food, I would get the 700g size, 12kg really is too much! Hamsters don't eat that much & even dried food will lose nutritional value over time so best not to get too much, I guess if you want to save on delivery costs getting two 700g bags might be a good idea.
Yes you do feed just once a day or even put enough food in for a few days then don't give more until it's gone.
It's best to begin feeding with a bowl if that's what she's used to but once she's settled in you can start to scatter feed, either scattering food around the cage or finding places to hide it which encourages their natural foraging behaviour.
They can do with a little extra protein for the first 6 months, after that the amount in Harry Hamster is perfectly adequate.