74 pages in the 'Next System' that don't tell me anything. Is there any particularly useful post in it?
The top part of the first post in the thread is kept updated with the current status, which gives the names and types of systems nearing completion. The ongoing recent posts at the other end highlight updates and discuss potential immediate targets. The bits in between are of historical interest only and you don't need to read them.
Here's a quick picture of how the states work (almost all of this information is in the galaxy map in-game, but you might find it clearer rearranged this way). We want the systems to be "Safe", the Thargoids want them to be "Control".
I'm still busy with engineering and if fighting Thargoids requires even more engineering and/or other upgrades, I guess the war will be long over before the engineering is finished.
For direct combat, Scouts can be fought in an unengineered ship with modules picked up from standard outfitting - especially if you're not the only person in the instance. Engineering helps, of course, but doesn't need to be total. The larger Interceptor-class Thargoids generally do need engineering and lots of it, but it's not essential to fight them to contribute: someone needs to keep the smaller stuff off the backs of the pilots who are fighting them!
For indirect routes to fight them, hauling and passenger missions are available which don't require combat at all in an Alert system, and only require running away (for which engineering may be needed to run away quickly enough!) in an Invasion system. If you're wanting no/low-engineering options to start with, then mission support to inhabited Alert systems is probably the easiest thing to start with. At time of writing, the Wolf 121 and HIP 20527 systems are the most progressed populated Alerts, which you can see in-game on the galaxy map, or out-of-game on the "Next System" post or the DCoH website. Some groups specialise in this sort of low-combat activity with minimal engineering requirements.
And I've been reading somewhere that the Thargoids have resorted to somehow corroding and shooting anything Guardian so that Guardian stuff doesn't work anymore.
This only applies in their eight "headquarters" Maelstrom systems (and one other Thargoid system not directly involved in the war), and people trying to hunt down their specialised Orthrus-class Interceptors elsewhere. The majority of fights the Guardian technology is still operating normally and I doubt that will change.
Can't we just form a couple fleets with like 500 ships each and invade our systems back? Something like that seems more reasonable than every commander trying to do something alone.
There's infrastructure in place to allow that sort of co-operation, but with so many different groups involved people have different objectives, so total cooperation on that scale isn't practical. Most systems generally - on an individual level - don't require that many players to recapture, so there's no need to focus effort that much. But there are well over 1000 players contributing to the 30-ish systems won each week, and relatively little effort is "wasted" in unwinnable fights as a proportion of the whole, so that's more or less what's already happening on a big-picture level.
What is research sampling? Somehow capture a Thargoid and shove probes into it?
Without the "capture" bit. Stand near a very angry Thargoid and probe it to wind it up further, then run away with the samples. That's definitely one of the "you probably want to be engineered for this bit" options ... though if the samples are then loaded onto a carrier, you won't need engineering to help unload them to the rescue ships at the other end.