You can get extra experience points in Farmville when you visit and your friend's farm and helped them fertilize their farm and vice versa. You get 1 extra exp point per fertilized plant with a maximum of 5 fertilizer per friend.
Experience points are shown underneath their pictures in the neighbors bar, Farmville cash/coins are private.
It means experience points.. hence the need to collect them to proceed another level.
At the top center of your Farmville screen you will see a bar with a star attached to the right side. This bar shows how many experience points (XP) you currently have and the star indicates what level you currently are. If you hover over the experience bar with your mouse it will show you how many experience points you will need to accumulate in order to get to the next level. As you increase your level, the number of experience points required to level up will also increase.
It earn you experience coins and when aggregated you will also get a mastery ribbon which will earn you coins and XP points.
If you got a gift of XP points, you will find it in your gift box. Open it and click on "use" below the XP points. It will automatically add to your experience.
You Level up or buy farmville cash. That's the only real way.
You cannot fertilize your own crops but it's your neighbors' who can do the fertilizing for you. You both will gain extra experience with your neighbor an extra coins for every fertilized crops.
No.
You get mastery points by harvesting your crops.
A friend of yours came over and fertilized it. Just leave them as is - and once you harvest them, you will gain extra experience!
Ferilized crops grow larger and yield more experience points when harvested. If the crop is a flower, it increases the chances of getting a "Perfect Bunch".
You should spend it on things that will generate even more cash or that will give you more experience points to get you closer to the next level.