For gaining standings through Storyline missions, it’s better to actually run level 3 missions due to the fact that they can be completed more quickly compared to level 4 missions, thus giving you more Storyline offers.
No, there’s only a small pool of Storyline missions and those missions are generally considered to be randomly offered.
However, years ago I did entertain the idea that the type of Storyline mission being offered may be related to the Agents Division or possibly the Agents Corporation. Course since Storyline missions are only offered after completing 16 regular missions, I never bothered to look into that.
Researching that theory opens up other possibilities to consider and investigate, like maybe the type of Storyline mission being offered is based on the type of the 16th mission completed, such as if the 16th mission was Mining or Courier, then a Security Storyline mission would be offered. Course on the flip side if the 16th mission was Security, then a Courier or Trade Storyline mission would be offered.
There’s just way too many variations to research and document in order to actually predict and or influence what type of Storyline mission will be offered.
Off hand I should just say no, but that’s not entirely true. It could be done but will require a lot of work. Main thing to remember is for access to high level agents above level 1, you only need to maintain Faction above -2.00 standing, as long as you have the required amount of Corporation standing.
In my first couple years of playing this game, I ran missions with Thukker Tribe for LP’s to get Thukker Shield Extenders. At the time those were hot selling high priced items on the market. I actually gained very high Faction standing with Thukker Tribe and noticed I was also incurring bad negative standings with all the other Factions (Back then Thukker Tribe had negative standings with all Factions, including Minmatar).
Some of those Factions were getting very close to -5.00 standing. (Players with -5.00 or lower Faction standing are chased and attacked by Faction NPC’s within their High Sec systems). Since I wanted to safely travel through all High Security systems for access to all Trade markets, I spent three months researching and compiling various tidbits of information on how to gain Faction standings which lead me to create, test and post ‘The Plan’.
In my opinion there’s no practical reason to have high positive Faction standings with The Syndicate, Thukker and or any of the Pirate Factions since they don’t control any High Security Systems. Like I said earlier, all that’s needed for access to high level Agents is to maintain Faction above -2.00 standing as long as you have the required amount of Corporation standing.
FYI - The Syndicate has positive standings with Angel Cartel and Serpentis Pirates which basically qualifies them as a Pirate Faction. However technically speaking, Concord has neutral standings with The Syndicate, The Society and Thukker Tribe, possibly due to secret payoffs.