If I install homebrew channel, will I get the 20102 error code when trying to Online Multiplayer?

I have read many articles of Homebrew users getting banned from Nintendo Wifi and I've seen some videos of it also.

So if I start using the Homebrew channel, will I have to use a method to bypass the error code?

No!
So far Nntendo only targets cheaters.

Don't cheat and you are fine!

1)As long as you don't cheat, you won't be banned.

2)Ironically, there is a cheat code that will let you bypass the error...

And I wish, the later would never have been discovered, or even be possible.

Exactly. It would be useful if Nintendo DID decide to block all homebrew users, but they haven't its only cheaters. And now they can cheat online again.