Well.... You don't really upgeade them BUT you can make them golden like Golden Fishing Rod - Catch every type of fish one time.
Golden Bug Net - Catch every type of bug one time.
Golden Slingshot - Shoot 15 items out of the sky, then you get it if you shoot it down.
Golden Shovel - Bury a regular shovel in the ground. Dig it up one full day later. It will be golden.
Golden Watering Can - Keep the environment perfect for 16 days in a row. Pelly or Phyllis will then give you the golden can.
Golden Axe - Trade a scallop seashell to Pascal for the golden axe.
You cannot upgrade your gate in animal crossing city folk.
No.
Yes
Nookington's is the last upgrade in the game and you cannot upgrade after you get it.
nothing i don't think.
it does it automatically, but paying rent helps (:
If by that you mean upgrade, then you get a basement added to your home.
At the bottom of the screen
You upgrade tools by using it and it levels up. To actually use the leveled up form, you have to go to the Blacksmith's shop in the Garmon Mine District to upgrade it. You have to get the specific ores required for the upgrade and a specific fee.
Just keep spending money and then you will get and upgrade.
the store will change upgrade but not move
To get Harriet's Barbershop on Animal Crossing Wild World, you need to buy things from Nook, so he will upgrade his store to Nookington's. The the Barber will be in the back of the first story.