Mostl likely let them lay around for 1h. They should change the same way, seeds turn into flowers. That is active time.
The passive timers like the grill or the sweet dessert or the green tree need at least two empty squares around them at the time the timer is up. and they are active time in home as well.
Depends on how much rubies you have.
Totally worth are the rubies in the maps. you can take them home and merge them up.
Anything you can farm in a reasonable time is not worth it. Anything you can not farm is potentially worth it.
When an event map comes, there might be shortcut items.