So, I know you earn SP passively, but what dictates the SP you gain each match? For example, are kills giving you 50 SP, assists giving you 25, and hacks giving you 100? I've also heard that squad commands give you more SP, but as I've never used the system, I have no idea what kind of bonus it gives. Does anyone know about how much SP comes from doing different things? Honestly, I think it's a bit odd that I go 5/12 and still end up with upwards of 25000 SP earned total.

The points you get in games are War Points, apparently. Your SP is calculated by a number of factors, one of which I can confirm is your gear. For instance, were you to kill a full-Prototype user with your Militia gear, you would a lot more SP than he would get for killing you. Also, the active SP gain is on a descending modifier set to kick in after a certain number of games, so that someone that plays the game for 8 hours a day can't just destroy everyone else within a month. The passive skill gain is also inactive right now, though I'm sure we've all noticed that at this point.

I've (occasionally) seen messages about what appears to be SP points related to specific weapons/weapon usage in game, ie. 'such and such a Forge gun, 135pts', or something similar. Anyone have a clue? Is this SP points adding to your weapon skills from in-game actions?

I also wonder how the end of game rankings are calculated. I don't get the impression they are linked directly to SP or kills, although they may be a combination. I seek enlightenment.

I thought so, too, but that's just your ammunition restocking - because you're near a nanohive thingamajig.