Welcome back.
I’ve a long background flying Amarrian ships and use the Apocalypse (Apoc) for missions - though I’ve largely moved on to the Navy Apocalypse (NApoc) and a Paladin now.
Fittings in detail are always skill dependant, and the Apoc with large beam lasers can be a little tight. I’ve always gone down the Beam with Large Micro Jump Drive so I can hit things at range and keep at distance to ease the pressure on my armour repairer - you need to manage the capacitor.
So, best Large Beam lasers you can fit. Training a good level of Amarr Battleships helps: beam laser tracking is poor and the hull has a nice bonus to it.
Mid-slots: Large Micro Jump Drive, 100mn Afterburner (not used much but removes the pain of crawling to an acceleration gate or wreck). A tracking computer with both scripts as an option. Tracking because it helps, range because that translates to more damage using a shorter crystal. The final slot is something to help the capacitor - a recharger works nicely.
Low-slots: a couple of heatsinks - making things go away quickly is a good defence - then a good active tank. T2 large repairer, damage control, suitable hardeners/costings/membranes to bring up the resists. This makes life easier for the repairer to keep up with the damage. Change the resist modules depending on the mission - though a reactive hardener does work it does need capacitor.
Rigs: Semiconductor rigs and capacitor control rigs to help with the capacitor is where I’ve often gone.
Take Navy crystals - at least MF, Standard and some intermediates. Take a crystal that has an optimum the same as your target range so if you can lock it you can hit it.
Take light drones to hit small stuff that gets under your guns.
You’ll find you can shoot as far as you can lock targets. Work your way through the targets, watch your capacitor, use the LMJD to move 100km away to reduce the incoming damage and gain a chance to repair and let the capacitor recharge a bit. Without T2 weapons it’ll be a lot of plugging away ar targets, but she should serve you well and you can upgrade as you see fit.
Aside: the Abaddon with pulse lasers is a miserable experience as a mission ship. Capacitor hungry, slow, bit short on range. You’ll be chasing targets you can’t keep up with. Tried it once. Regretted it.
The NApoc is just “a better more powerful Apoc” - more firepower, better defence, better capacitor, bit expensive.
The Paladin is an optimised Level 4 mission slaughter machine. And a really long train an rather expensive.
A Tachyon fitted Nightmare is also worth s look, but requires good shield skills and Caldari Battleship Skills as well - and like the NApoc is an expensive hull.