Your question about how long you should let your hamster out is really interesting. Maddy is out as long as she is reasonably active. When I let her play in the lounge with us (it's barricaded and completely hamster safe), I bring in lots of her toys and let her explore. When she gets tired, she goes to sleep in the same place she has done since she was just a little pup. If she sleeps for longer than ten mins I put her back in her cage. When she's out and about I also bring in her food and some water.
Whilst Maddy will come and say hello to me she is largely independent. I sit on the floor with her and give her some hugs but she doesn't stand it for long and she has always preferred mooching around on her own. I wouldn't take it personally if yours is like that too. When your little one grows in confidence you'll find that you'll have more interaction
good luck