Pantheon is a top tier jungler, and a great mid/top.
As for farm 1 kill is worth about 20 cs worth of gold; it's definitely worth trying to farm well. As you get better at the game you'll learn to cs, avoid harass and put it out as effectively as possible.
As a high elo player I'm satisfied with about 8 cs a minute. Can be higher or lower depending how in control I am in my lane.
Later in the game be aware if a lane is frozen on your side of the map. If unattended your creeps will arrive sooner and cause a slow push and your team will lose a lot of farm in that lane as your creeps pile up to a big fat wave for your foes to eat outside your tower. Mid game you want to keep to minion waves pressured on their side then roam/gank other lanes and force your foe to lose farm following you. At least that's what I do because I don't like split pushing by myself.
Could write a whole chapter on early game laning/trading/farming/wave control... Just be aware when you push you get a temporary exp and minion advantage you can use to abuse your lane opponent. If you don't push too fast you can find opportunities to catch them if they step up to last hit maybe with a level advantage even. If/when it's frozen too close to his tower finish his creeps off so the lane will reset after the tower kills all your side's minions. Just ward and watch out for junglers.
Pantheon is very strong in lane because of his spear harass. Abilities won't draw creep aggro unlike your auto attacks.
