First of all - I hope you and your son and friend enjoy the day/game!!
How old are they? It might be cool for them to go see Husky Walk. That happens a little over 2 hours before kickoff when the team arrives to the stadium from campus. The boys will be able to high five the players and coaches as they make their way into the stadium. We've taken a few kids over to the Husky Walk over the years and they have all LOVED it.
If you get to the stadium after Husky Walk and are just interested in going to the game, then I'd say arriving at Silver Lane 1 hour before kickoff would be just fine. That will give you plenty of time to park, make your way over to the stadium, get food/drinks, and find your seats in time to see the band bring the team out of the tunnel.
Unfortunately, there is a strict "No Food/Drinks" policy unless your kids are really young. The good news: the concessions have improved over the years. If you and the boys can't find something you like in the stadium concessions, there are food trucks located behind the scoreboard/Jasper Howard Memorial. NoRA cupcakes and a few grilling restaurants were back there for most of the past few seasons. The prices are typically the same but the quality is typically better. A few Yarders were able to go the scrimmage yesterday and have reported that a Texas Roadhouse concession opened. That too is a improvement over early Rent concession options.
You picked a good game for the kids. Watching the Army cadets take their seats is really cool. I would guess that you'd have to get your way into the stadium a bit earlier to see that. If you and your kids have a good time at the game but miss the cadets, you'll be able to recreate the honor when Navy comes to the Rent later in the season.
HAVE FUN!!!!