if i get an older wii with system software under 4.3, should I update it to 4.3 before installing the homebrew channel?

does the homebrew channel worker better in the older firmware?

No it works the same on any version of the system menu you have, You can install home brew before or after its your choice, if you update first you can use letterbomb on 4.3 as it does not need a game to run the exploit.