If some random monsters leak past your chokepoint, don't fret! send the next wave and your reinforcements should be all ready. Remember, wave skip time is not real time!
For xp, you should use the vault challenge (go on daily challenges, previous challenges) and go to February 7th. This is a challenge that starts on round 85 and goes to 95: you get 200,000 cash to start on medium with NO RESTRICTIONS. then, spam super monkeys, if you have sun god, spam that. Else, just get as many as possible (under monkey villages to make them cheaper) until you unlock it. You should use all your starting money. After that, spam whatever tower you want to lvl up (don't upgrade) until you have all upgrades, then sell all those towers and start on others. Remember, even if you lose, you still keep the xp!
daily badge is easy: In your home town just fight the champ, then you lose cos they so powerful. Daily badge done, don't complain about the game being bad.
Yo dawg, I herd you like grinding, so i put the grind in your fun so you can grind while you grind while you grind while you grind while you grind while you grind.
Wait... if he runs this place, then he could just promote himself to top rank immediately... Better yet he does all the jobs and so is all of the ranks at once...
Slow but effective Farming: (make sure you have auto-click, decent wep [can kill armadillos without them getting past mouse] and auto-collect if super paranoid) Go to Animal Lair level 1, put mouse on mushrooms but just toward the lair a bit to make use of full wep range. Then, right click and click outside game screen. Done correctly you should get your wep killing the armadillos whilst you do something in another tab.