Do you have to put a new electric meter right next to or under your breaker box? I have a new addition and the main breaker box is on the inside hallway wall on the back side of the house. Do I have to mount the meter box next to it or can I mount the meter on the front of the house and run the main electric wire in conduit going to my breaker box in the back of the house?

My home was built in 1998, Phoenix, as I've been upgrading electrical switches (motion sensor, wifi, etc) I've noticed all of the grounds wound together and never attached to the original switches. In researching what I found was in older homes it was permissible to do this? Is that true? It's a pain to unwind and attach to a ground, but for the new upgraded switches it is required. Should I just go ahead and attach the grounds to the old switches as well while I have it all open? The box is plastic, does that make a difference in how it was originally wired? I've been cursing the previous owner lol, but probably they've been like this since the build. Appreciate all the help and advice in advance.