Put bulbs in an old colander or mesh basket and plant the container straight into the ground. This way you can keep  colors together, Keep the mice away and it makes digging them up at the end of the growing season much easier.

Hardyness zones are an indication for the average lowest temperature in a specific area.
Almost all bulbs do well in US zones, but some bulbs need special treatment in extreme heat or cold area's.

Take your zone into account when buying bulbs but be aware that your zone is an indication and that specific situations in your garden can create micro climates that deviate from the hardyness indicated.