Yes its normal and yes they will flower throughout the summer outside.

Should do. You can pinch out the growing tips to make them bushier. What are you growing? Some may not survive a late frost......Maybe begin to harden them off in a cold frame, this will slow their growth a bit too. You are a bit further north than me so have to be careful.

I put all my bedding plants/tender new perennials, outside in the morning and bring them in, in the evening. I call it the greenhouse hokey cokey.

I would keep them well fed, and pinch out all of the flowers and older buds when planting them out. That will make them concentrate on growing roots for the first few weeks, for a better show long-term.