[Emulator] Newbie Trying to learn

I would like to take a step into making an emulator. I know it'll take me a VERY long time, but I would like to ask some questions as to what I need to know.

I know the best language to use is C++ right? or wrong?

How would I start it and what's the easiest way to decrypting packets.

I would like to make an emulator for Tales Runner or Operation 7. Does anyone know any tips that could get me on my way? I would like to make at least the login server by myself before asking for real help.

You should try using the search button at the top :)

It'll give you posts similar to yours that have already been answered.
Maybe you could get some help from there.