S rank comes from the Japanese academic grading system. See below:
rade in Japanese (Kanji)
English translation
Corresponding percentage
shū (秀)
Exemplary, excellent
S (90–100%), rarely given
yū (優)
Very good
A (80–89%)
ryō (良)
Good
B (70–79%)
ka (可)
Average, pass
C (60–69%)
nin...
Haven't even looked at island rating but I'm really reluctant to do sink significant hours into designing something only to change it the moment I get terraforming. At the same time I'm nowhere near unlocking terraforming so it's a bit of a pickle really.
I didn't know customising tools extend their durability- thanks!
Also, if you really want bushes/hedges, I find that getting a hay bale and colouring it green works ok. Good luck!
There's just so much to do andlook forward to. And besides, the beauty of AC is if you don't play for a while, you'll have hours of catching up to do to see what you've missed, land maintenance, new dialogue etc