Port forwarding won't do anything to a changing IP adress, that is assigned by your ISP. Most ISPs provide a semi-permanent IP adress, or change it max. once per day (often at midnight, which is inconvenient for gaming).
Fighters have the equivalent of 2 medium weapons, and are quite good on the offensive, as soon as they gained a few ranks. They don't get lost forever now when you blow up, they just add a little bit to the rebuy.
I don't know what got deleted from Thargoid combat, AXCZs have been missing for a while but apart from that it is still the same old, with a few tougher variants at the upper end (depending on where you draw the line). It is also totally opt-in (too much IMO, where is the threat of them?). You may encounter one when they interdict you, but if you ignored them and anything related with them, they won't do anything except scan you.
If you don't want anything of that new Horizons stuff, you can still just forgo buying the Horizons only ships, never land on a planet, don't accept missions requiring you to do, and forgo engineering. You will still be able to do everything you could do before Horizons, fight (no Thargoids, those are Horizons+, only do Low Intensity Conflict Zones, those are still as easy as the old ones were), explore (don't use the FSS, just fly there old school and scan, don't use the DSS since that is also newer), mine (but please, only surface laser mining), trade, rares. It is all still there, so I am at loss what could've been deleted. It is also still all possible to do, without engineering. It just pays more than before.