Kingconga

I have no objective answer for question 2, but I believe it is just as rare on most routes it appears in. As for question 1, by fishing you may encounter all Pokemon you normally encounter by surfing in addition to all fishable Pokemon. This alone (I believe) is what makes some fishable Pokémon such as (Shellder?) Staryu and Dratini so rare. I'm pretty sure you require a Super Rod for Shellder. I've personally tried to fish for both Shellder and Staryu using a Good Rod for two in-game nights each to no avail. They only showed up using the Super Rod.

You can see his happiness above the hp bar its that orange one with the smiley. You can also use the "/happy x" command in the chat window. Replace x with your Pokemon's number in party. Example: /happy 1 Displays your lead Pokemon's happiness.

Subbed.

Exp values vary depending on the difference between your pokemon and the opponent pokemon. The higher your level is compared to your target, the lower exp you get. The opposite seems to be true. 420 and 666. It's just a coincidence.

Welcome PinknBlack! Yay a fellow pink lover.

KingConga here. Nice to meet you. Currently going through Johto.