Entrances should be the size that the bees can defend. If the colony is smallish and there may be a danger of robbing reduce the entrance down to just enough space for two or three bees to pass in and out. As it gets stronger the colony will benefit from a wider entrance so more bees can pass easily but also so air can be circulated to dry nectar down to honey.
What you describe should be fine.
What you describe should be fine.