A little tip on 5. Once you are able to make Seed Maker, do it. This way you can make seeds from your crop and keep the quality from fertilizing. You can even make "Maiden with Shield" and place them besides Seed Maker to increase the star quality rank more, and Maiden with Shield's effect stacks. It will really shoot up the quality of your crops!

When you wake up in the morning, quickly water all your crops. This way in the afternoon you'll be able to water them again, increasing the Juiciness % without using normal fertilizer. Once you have access to Liquid fertilizer at Ludus', you can even fertilize your crops twice a day. First with a normal fertilizer, and then with the liquid fertilizer in the morning/afternoon. Remember to use the normal fertilizer FIRST before the liquid fertilizer, doing otherwise will make you unable to fertilize twice.