Good idea on the hole. I've been just aiming to hit it at the right angle.Nope, but if you're harvesting them every day it shouldn't be much of an issue. Be sure to dig holes behind you to make sure you get the full 9 hits out of each. Personally, I've only been to about 3 islands, now a week into my town, and haven't been blocked by resources. That said, once the work week hit I slowed my pace of progression considerably.
Rock tips: http://www.nintendolife.com/news/20...n_nuggets_clay_stones_bells_and_rock_respawns
If you can't replace rocks, why allow them to be broken?