Question 1: You can ask, however every builder has a preferred manner of working, so you get what the individual is willing to give. I personally dislike ballparking costs (creates expectations that may not be accurate) and would rather give an estimate based on a well developed plans.

Question 2: Most tfers will to some degree want to produce shop drawings. Expect your plans to be marked up, expect revision and be willing to accommodate stated needs through the building process or you can release the reins a little and allow experience to have a voice. I fear that you may be setting up a situation that devolves into endless haggling.