Hiya!
it's one of the things I wish were different, so many things don't work when you are visiting each other (or even just have the gate open) that it's hard to show other people how to do stuff or I would happily show them
one important question for the second is: Has KK Slider visited the island for a concert and have the girls got the landscaping ability?
If they do they have the icon on the nook phone with the hardhat that I've put a red thing around.
So: unlock KK slider by going to Tom Nook and asking"what shall I do" or some such, after the concert (and credits btw) you get the icon. In the Nook machine you can buy additional "permissions" but all in all this gives you the ability to make paths, fill in/create rivers and ponds and create/destroy cliffs
but not when your gate is open
the other thing has to do with designs and you need a stone Ables clothing shop.
In the shop you find at the back, like a touch screen slab (not so good at words atm as have migraine)
in that you can look up designs to move to your nook phone
you have to look up what you want before hand, I usually find them by accident or by browsing
https://nooksisland.com/designs so a sand one you can search
https://nooksisland.com/designs?search=sand and save the one you want
and then leave ables, go to the spot you want it, go to the pink icon that I've put the blue thing around
choose the one you want and say "display on ground"
I usually put the creator ID in the search at Ables because a person might have many great designs
now this is also a work around thing for paths if they dont have the other icon yet, because there are plenty of lovely path designs, it just takes time and patience to lay each design one by one, but it looks lovely
https://nooksisland.com/designs?search=path couple of things about design: they can be wiped out by Y but easily put back
there are limited design spaces in your nook phone, so be careful of designs that take many spaces
because once you use a design, it needs to stay in your nook phone in that spot or it will be gone from your island too, or replaced with what you have overwritten it with
by searching the website you only find english language labels, by searching on google, pinterest etc you can find lovely designs that you would not find by searching the site
sorry for the rambling story, hope it helps at all, pls ask additional questions and I hope my brain will work gooder