Early defence stations are critical, if only to ensure you can actually get those Pirates to fight you. The Rally Point system in it's default settings works against you; those new ships are still eating that warp time. Effectively your new planets, if any, will be isolated and alone.

You're potentially going to be in this state for a WHILE; for example, by the time my Wormhole tech finally showed up, I was at Cruisers and X-ray Lasers.

How is the mix between defense stations, spaceports, and local fleets?

Hard to judge for me. I'm...well, I'm modded to the hilt. But the Pirates never mess with proper Spaceports or even colonies in any case, only the isolated Mining Stations. That's why you want the stations. Every time they show up, I don't have much infrastructure to lose, nor much means to build more.

You can kinda abuse the targeting. When the pirates kill a station, they'll head home. If you've targeted your fleet to fight theirs, they'll track it home. Thus, you now know where they are rather than the blind hunt you normally get.

Of course, good luck getting hold of the debris unless you've built a Science Ship specifically and sent it along that way as well.

Is it possible to get a pre requirements list for all the techs that have been added / changed?

FTL techs are the only ones changed, they now have a single theory prereq for each type.