1. The facilities you would want to build are really dependent on the situation and on what you need. If it's a world bordering an enemy, you might build a shipyard, resupply depot, and maybe even cargo facility to store mines, satellites, troops and/or platforms. If you have other planets in the system, you can put your spaceport on the small planet to leave more room on the big ones for other things. If you have high enough tech, you can put system-wide improvement facilities on the small planets so they don't take up room on the big ones (ie: system robotoid factory, nature shrine, med lab, system computer center).
2. I think there was a bug in the game (demo Version only?) that allowed people to build more than one shipyard on a planet, which made production go much faster. I wouldn't recommend that.
You can put space yards in ships and star bases, also. I put star bases with space yards at my homeworld and other places where I need to have extra production queues. They let me build more ships while I'm also building facilities on my planets. Putting a space yard on a ship lets it be mobile, so you can, say, move the ship to a wormhole and build a battle station there, or put it in an attack fleet to help you build new ships and bases as you advance.
3. The manual covers all the assorted game windows and options very well, but it doesn't give much playing tips or game details, but definitely read the FAQ part of the printed manual. For gaming tips and strategies, read this forum and I also recommend SE4 Center forums at:
http://pub4.ezboard.com/fse4centerfo...ceempirestriad
4. The max number of systems is 255, which you can set by editing the Settings.txt file in the data directory of the game. If you do that, you also need to add more system names to the SystemNames.txt file in that directory or you will end up with blank system names. If you can't think up an 150 new system names, look down a bit in this forum, you'll see a post by me saying "need system names? Get 'em here" that contains a very long list of system names you can use.
Other than changing the max planet number, just make sure you select the biggest galaxy size when you start a new game. Also, don't pick the Ancient galaxy type, which results in more black hole and dead systems.
5. You can set the general amount of computer players when you create the game, but it seems that number scales with the number of systems. I think in my huge galaxy, the medium setting gave me 8 computer opponents and the lots setting gave me 14 opponents. So maybe few would give you the right amount.
But with such a large galaxy, that will be quite sparse, since with only 4 players in total, it would average to be 60 systems per player!
In my current game with 9 players in a huge galaxy, it took me at least 50-60 turns just to make first contact with _anyone_. The AI doesn't seem to excel at this sort of peaceful buildup so I'm solidly in first place and pulling away quickly. In my next game I'm going to add more opponents so that I have some earlier challenge.
In a hage map game with only 4 players, you can probably dominate the game such that victory is assured without ever encountering the enemy.
6. For more tips on the game, go back and read the old Posts in this and the SE4C forums.
Have fun!