What are some ideas and tactics you guys have come across?
If your economy is running well, you can actually make static defenses hold off some pretty big attacks. It just costs a lot. The key is in making sure your constructors don't get hit by much. AI will generally ignore targeting them directly, but secondary capital ship weapons can fire at them, and any splash damage gets them too. But if you have a planet fully upgraded in logistics/tactical slots, you get something like 4 constructors that can build 4 turrets at the same time. This means if you can keep them alive, they usually build faster than the turrets get destroyed, especially if you have 3-4 repair bays. It starts getting bad if the AI has a lot of carriers, because bombers love targeting your repair bays, and that throws the strategy off balance. Still, I've defeated quite considerable fleets by doing this.
The better option of course is not to have a second front exposed. If you're playing with unlocked teams, always try to get a cease fire going with one of the AIs bordering your empire. He won't attack from there, and he'll keep another AI busy too.
If you do keep ships to defend, I would just build a bunch of LRFs (Javelins, Assailants, Illuminators) so they can hide behind the turrets in relative safety and add quite a lot of firepower.
Second question: How exactly do trade ports and orbital refinerys work? It seems that they result in different resources/per second in each game. What are the fine details about these things? Does it matter on which planets I build trade ports? Does distance matter? Does population matter? How can I maximize my profits when I'm building trade ports and refineries? Right now it's just guess work.
Trade ports are pretty basic. You build one, and it generates a set amount of income. You can stack several ports per planet, and each one will add the same amount of income. Allegiance doesn't matter, population doesn't matter. You get a bonus to trade port income along the longest uninterrupted route (hover mouse over the credits to highlight it). Building trade ports on planets along that line (and trying to extend that line) will give bonus credits for those ports. Pretty straight forward.
Refineries are a bit different. For TEC and Vasari, a refinery services *all* mines one jump away from the planet it's built on (and including that planet, obviously). Each mine on a colonized planet has room for 3 refinery ships working it, so 3 refineries will max it out (neutral mines that you can capture can support 4). Basically, if you have planet A connected to planets B, C, D (the connections between B,C,D don't matter, just that they're all connected to A), building 3 refineries on A will max out resource production from all 4 planets. Advent don't have a separate refinery structure, they have a research tech that gives its trade port the ability to change to refining mode, which provides a much bigger bonus to mine income on that planet, but it doesn't produce any ships to go to neighboring planets, so it's just the planet it's built on.
Hope this helps some