Very incorrect.
A - There are some great ones there, including the starters.
B - They give you LOTS of candy for evolving, which gives you XP
You get spare incubators from poke stops, so you can use your breakable ones on the 10k while your default unlimited one chews through the 2ks.

Strongbad’s dragon has already given some good tips on fighting, but I’ll overview for thoroughness.

Repeatedly tap the screen to use your basic move. I’m working on the assumption that faster tapping is better. You’ll see one or more blue bars fill in as you tap (which is why I’m going with faster is better). Once a bar is filled in, hold your finger down on the screen to execute your secondary/special move.

You can choose which attack your pokemon should use in gym combat:
If you just tap, the pokemon will use the first attack (quick and spammable)
If you hold, the pokemon will use his second attack (slow but deals greater damage).

Step one: Open app.