Home designer or builder

Building on a lot about two hours away from our current house. Have a local house designer (who works with an architect) that we know and trust. Does he decide where to place the house on lot or is that something builder will do later? Would/should a house designer travel two hours to see the lot (25 acres). Also, we will need mound system and well. Does that impact house design or again is that more of a builder issue later? Thank you!