1. We don't know if you changed the game enough but if people play it and say things like, 'this seems a lot like Monopoly,' the answer is probably, 'No.'
2. If the only thing the games have in common is the idea of purchasing property, then you're not likely to be infringing.
3. If the game infringes, you will be liable for selling, distributing or licensing. You don't have to make a profit to be an infringer.
4. If it's not similar to Monopoly it won't infringe even if you were originally inspired by Monopoly.
5. We don't know if you should go see a lawyer. We happen to like lawyers and think they're an interesting group of people. But that's just us. Also, when we speak to lawyers, the meter is usually not running. We would suggest holding off on the legal visits and learning as much as you can by yourself.
6. You may be able to patent your game--possibly with either a utility or design patent--but we wouldn't recommend it as a strategy for board games (which kind of fits in with the whole twisted legal history of Monopoly). In any case, copyright and trademark law should do just fine for you.
7. The Dear Rich Staff used to do a lot of toy licensing and our experience from that was that board game licenses were exceptionally rare. You will have a hard time getting in to see the two or three companies that still make board games, and without major distribution, it will likely become a money-losing venture. Even if you do license it, the chances of breaking through the existing pack of popular and classic board games is slim. (Sorry to be so negative but we're glass-half-empty folks).
8. If your game isn't substantially similar to an existing game and doesn't use a similar trademark, you're legally entitled to do what you want.