2019LHP:
If the coach is considering sending your son to the NECBL, consider him very lucky. Most polls/listings rank the NECBL #2 behind the Cape (Sometimes Northwoods is #2 & NECBL#3). It's a great league, the cities and the level of competition. My son got a "taste" of the NECBL as a rising sophomore (after his American Legion season and AAU were winding down) for one team. He was a starter as a rising senior for the Valley Blue Sox (out of Holyoke, MA). Great memories for me watching him go 6 for 7, 5 runs scored in the championship win, which was a nice way to have your last college summer league game
The core of position players will play the entire season (unless let go, injury, or loss of commitment). A number of pitchers came and went as they were on "pitch counts" especially if their team went deep in the NCAA tourney. So rosters had some flex, but no where near what the Cape does. NECBL may pick up a fewer players after a Cape 10 day contract ends. It goes the other way too- a player may be asked to join the Cape after his team is eliminated from NECBL post season (geographic proximity helps).
There is a set fee (I forget what it is); you can find it on the website. There are host families (helpful but not required to have a car). Daily meals are provided by the host families and dinner is after the field(Both home and away) after games. The league prepared son for his senior year as he faced some pitchers from P5 programs - and played with and against a number of "All league" players. Outside of occasional & unusual scoring decisions (H or E) and live stats freezing, no complaints. The games are livestreamed for a fee (game or season). The coverage varied based on what ballpark you were playing. Living in New England I got to watch son play in cities I probably otherwise wouldn't have visited. The Blue Sox had their own bus; other teams I believe had rental agreements.
To COACHLD: Kept hearing how Montpelier was the only state capital in the U.S. that didn't have a McDonalds.