Regarding specifics, here is what I remember from my game:
The game will have three main phases. The blitz, where the hornets are let loose and you do nothing but attempt to survive the onslaught. Pre-blitz is when you aim to consolidate power without triggering the blitz and post blitz is when things calm down because the galaxy has mostly been torched.
To start, you will need to use champions. You need those special fortress rewards for your chokepoint and those extra ships as well. The nenzul variant, with its cloaking will be your best friend as you try to avoid stirring up hornets in a dash toward the special wormholes. That same nenzul variant can lead any charge onto enemy homeworlds post blitz. I still think that ship has an exploit you can use so experiment, I just can't say it because Arcen would then fix it.
Regarding your bonus ships you need a ship class that is cheap. You will be throwing that ship into the melee that occurs during the blitz, with the hope it takes blows to keep more vulnerable ships alive. In other words you need younglings. I prefer fireflys because of guaranteed AoE. Nothing fancy about them. Build 10 space docks on your chokepoint, loop the build order with nothing about them, press ctrl + V and click the neighboring planet with the most dark spire. They will fend off any threats on your world first, then they will make it to the other planet and tie up the dark spire there rather then your own planet buying you valuable time. Don't bother with regen chambers; You need the nenzul to do the dying so your defenses do not.
As for map layout, you need a solid chokepoint. You will probably want at least 2 planets behind that chokepoint to supply it, but more is fine as long as no dark spire structures exist that could backdoor your fortress world. You will also need a map that features champion wormholes with the nearby ones not blocked by dark spire structures. Once you get the cloaking from the nenzul you get a little leeway, but you still should reroll if you cant get 3 or 4 wormholes in peace.
As for exo-sources such as golems, etc. I would not consider it worth it. Most of those craft are not really effective at fighting the dark spire to begin with, and the threat of exo-s disrupting your pre-blitz plan is the worst.
Regarding order of operations, establish your chokepoint and develop planets behind it as normal. Afterward, you will be looking for ways to increase your power with the understanding that anything beyond your chokepoint will die during the blitz. I would consider it wise grabbing an easy research station or two (with the goal of more cheap ships, especially younglings) and doing enough champion stuff to get at least one racial fortress. Don't stir up the AI to much pre-blitz, be strategic. The more the AI is stirred up the longer the blitz will be as the AI recovers ships faster.
For your fortress world you will want a MK III military station. You need the damage boost and the tachyon beams, and extra railguns don't hurt either. Fairly standard defense layout except all your unique defense toys go on one planet instead of being spread out.
I'm sure I am missing something, I'll come back