First few days after birth

We are due with our first little one in a few weeks. I am planning to breastfeed (nurse and pump and bottle feed after 6 weeks when I go back to work). I am still a little confused about a few things:

1. Is Colostrum alone enough for baby in the first few days until my milk comes in?

2. How long should I “nurse on demand” to build my supply?

3. When should I introduce a bottle so Baby is used to being bottle fed when I go back to work?

4. Is it possible to bottle feed and breastfeed? Will baby get too confused?