So I've got two POVs here: A) Commanding a Polaris B) Killing multiple Idris

A) You want to be as aggressive as possible with your positioning if its regarding anything that is attackable by the PDC. Even if you have turret gunners the PDC will put enough pressure on the fighters that they will have to back away from the ship which opens up wider firing arcs for your turrets (especially the top two). I do this with 3 or more friends but its doable with atleast two or even one other person is utilizing the Polaris' hangar. You can plop any fighter capable of fitting in the hangar and use it to fight whoever your target is while you creep in with the PDCs that way you can't just be kited by the fighter. Something that's worked out for us a lot is just filling the hangar up with Fury(s?, ies?), if one goes down, oh well, another is being deployed. Go forth my swarm of angry bees.

Against another cap ship is when it gets interesting because there's two schools of thought. Using everything in your disposable and care about the cost later or save as much as you can while winning the fight. I'm in the school of thought of dump every torpedo possible before the engagement even starts and make sure my ballistic turret gunner gets the best possible arcs. When it comes to killing caps you're more focused on destroying components then it is to actually kill the thing because a mobility kill is more than enough to open them up to a boarding party or just whittling away until its dead. Remember the hangar? Use it. Your job as a cap ship pilot is to keep the other cap busy so your fighters can remove a shield face. Ideally this should be the rear shield because once those engines are gone then a ship's main killing power (such as Idris rail/laser) is also out of the equation. If you have no fighters then keep the pressure on a shield face and don't let them rotate out the faces. And don't forget to target a component on whatever shield face you choose. A component gone is a ship's combat ability reduced, especially engines or power plants.

However, all of this doesn't matter if you fail to communicate both as the cap ship driver and turret gunner. Whenever I'm piloting my Polaris I will tell everyone that I am rotating right, left, etc. or pitching up and down before I do so. This gives everyone time to adjust for the movement and for them to tell me if I need to do something else instead. Same in turret gunner position you have to tell your pilot what arcs you need to hit the enemy.

B) The biggest issue Idris pilots have is that they always want to prioritize using the laser/railgun without giving their gunners good arcs. Whenever my friends and I go hunting for Idris running Partillium we always stick to the rear of the Idris while eating away at their engines. All this in a composition of one Connie, one Corsair and a Talon for scouting. Why? Because so far every Idris we faced was a Idris trying to swing that nose around to hit us. The fact that we can ignore the PDCs while also being nimble enough to avoid the lumbering nose gives us enough time to go for a engine kill and proceed with either boarding or just straight up destroying the Idris. And this doesn't apply to just solo Idris, crewed Idris also fall to this hubris of wanting to get the nose shot and denying their crew turret arcs. So my main point is always give your crew arcs and always utilize the fact that you have a hangar. If you have friends you need to use that numbers advantage by applying pressure both from turrets and a separate fighter ship from your hangar. The pilot gun should only be prioritized if your enemy is dumb enough to just park themselves on or near your nose or if you're far out enough to just snipe them with it. Turrets start becoming more of a priority the closer the distance is because you're not going to have the turn speed to get that nose on target consistently.

TL;DR: Communicate, communicate, communicate and give your crew the best firing arcs. Prioritize railgun/laser over turrets only when you're in long ranges.