What constitutes a "p"? Is it the same as experience? Do I get experience/gold from killing an inkling? (How much? Does that amount change?) Do I get experience for covering ground if it is re-covered by the enemy? Do I get the same amount of experience for covering the enemy's paint as for covering none? I know walls don't count for winning the match, but do they count for experience/coins? Are there any weapons or items that increase coin/experience gain? Basically, how does scoring in multiplayer work?
While I cannot quantify everything specifically, I can answer some of your questions:
- experience is the same as a "p" -- as far as I know, you get the same amount of gold as you do experience each round.
- you do get points for re-covering ground. In fact, this gets you more points than taking fresh ground.
- walls do not count for anything, they only help you climb them
- there are no weapons that make your point gain go up, however some weapons are easier to score with than others. Rollers and the Aerospray RG are great weapons for covering a lot of ground, and Chargers are a lot harder to cover more ground with.
For leveling up, I recommend using a roller, then the Aerospray RG until level 20. Then you can play basically however you want, since experience doesn't matter as much (it will only be used to level up gear at that point).