(1) I wouldn't be heartbroken if I had to move them but I certainly prefer not to. It is cool knowing that I placed those blocks 10+ years ago. (2) When I started adding signs, oak was the only type, I guess it never occurred to me to use another type. (3) Probably building item farm machines (iron farm, mob farm, etc.), I have a bunch scattered throughout the world at this point.
Haha good memory! I don't play Minecraft as much as I used to but when I do it is typically on this world. If I ever feel like starting fresh or if a new update comes out, I'll fly out into some newly generated terrain, drop my elytra & equipment into an ender chest and "start over" at the new spot until I get bored and want to head back to the main base. It allows me to have fresh starts while still staying in the same world.
When I run out of things to do or if a new worldgen-related update comes out, I'll fly out into new chunks and "start over" in a new area of the world. I pretty much always end up back at my spawn base after some time though. I've built a handful of smaller bases around the world this way. It's fun to explore and stumble upon things I built 5-10 years ago.
Thanks, it is a fun little tradition to have. I might need to make some more room for signs in a few years..