1) To get the mermaid Leia befriend Daryl You know he's your friend when he starts talking about cow cloning Then go down to his basement and you will meet her
2) To make crops a higher level you can plant them in the room behind the waterfall
3) To get a horse sell 100 items
4) To get the fishing rod go into Gallen's house at 12 pm with no tool equipped
5) Jewelry is found in the mine (where Flora and Carter walk) when you dig the ground with the hoe
6) Once getting the big bed and your rival to a red heart you also have to collect at least 60 Harvest Sprites