My suggestions:
DH to the NL has to happen. Pitchers hitting is stupid and pointless.
Marketing the game better also needs to happen. As mentioned encourage players to be themselves and as over the top as they can be. That's what sells today. Harper is the closest thing to a mainstream star baseball has. They need more. I remember Bautista's bat flip led off practically every ESPN show the day after, and ESPN has been slowly phasing baseball out for years now. Give fans a reason to care.
Make the league minimum $1m (year 1 is $1m, year 2 is $1.5m....something like that). Players become arb eligible after year 2, and players receive a buyout (say, $750k) if they are non tendered, since I'm pretty sure teams will go on non tender sprees if arb starts earlier. It's not the perfect solution, but will improve the players 0-6 years earnings, and won't be too big of a hit to the owners either.
I'm on board with the 3 batter minimum. I know some hate it, but pitching changes suck, and a RP having to face 3 batters means they actually have to be somewhat good, rather than a specialist. The less mediocre pitchers we have to watch, the better.