1. What was the approximate width of the crossing point of the Red Sea by Israelites?
2. Could that dry path created in the Red Sea be wide enough to allow all the ±5,000,000 Israelites cross the sea in one night with children and luggage? Another miracle?
Since we don't know exactly where the Israelites crossed, it would be hard to put a number on the width of the sea at the unknown spot. However, take a look at the map (click on it for a larger copy).
The Israelites went from Ramses to Succoth, from Succoth to Etham, and from Etham to the edge of the Red Sea each in a day's journey. Judging from the map each of those legs were longer than the distance across the Red Sea, so it did not require an additional miracle to get all the people across in one night. It is about 25 miles from Ramses to Succoth, so that seems to be roughly the distance this group could make in a day when in a rush. The other two stages were about 11 to 13 miles apart. The distance across the Red Sea is roughly 12 miles, depending where you measure the crossing, so it was a typical travel distance for a day's journey.