If you are wanting to sell more than 5 things (the amount that your bag can carry) you can go and drop the items that you want to sell up at the top left corner of your farm. There is a small patch that looks greyish-brown and if you drop items there then go to the shop and hit "sell," those items will show up on the sell list.
Instead of making multiple trips back and forth you can just drop everything on that patch of land and make one trip to the General Store.
To unlock new animals, you have to purchase and grow up animals that you have not purchased before. Once an animal reaches adult age there is a chance that you will unlock several new animals.
To unlock new crops you must do the same thing as the animals - purchase and raise crops until harvest. When they reach the harvest period you will unlock new crops. However, to unlock the sage, garlic, plums and oregano you have to cook and share existing crops with the villagers.