1) There are "Economic Stimulus" options, which will simply put extra work that turn into creds.  Although this means you'll have to keep an eye each turn if you have future plans for the planet after research has been completed.

2) I noticed the same thing--though I'm new to the designer, so I figured I had stuff to learn about it still.

3) Fact.

4) Use the middle mouse button to rotate your ship.

5) Still developing my own opinion, but interesting idea you have.

6) I have no idea what you mean, I mine the Durantium deposits all over the place, but perhaps there is the tech later on which is required?

7) No opinion currently.  I haven't played much.

8) I think you have the option in the bottom left to Obsolete them, however due to the nature of how complicated ship designs can be, "Auto-Obsoleting" may never be possible.  Range vs Speed, this laser power vs that laser power + shield strength, etc.

#6   Astroids can not be mined as they were in Galactic Civilizations II at this time, maybe in the future there will be something as mentioned in several of the dev streams.

1. Set to the manufacturing on the spending screen to 0. If you are not producing any manufacturing points, then the game won't bother you with idle planets. Alternatively, you can divert all manufacturing points to the shipyard, then it is only the shipyard you have to worry about.

Or pick a project and it'll do something else with their manufacturing points besides building planet improvements (like produce money, research, or culture). However, projects like birth subsidies or assembly relate to population growth (so there is a point where they are done) but they will never tell you that they are done, so you will have to get into a habit of checking in on those every so often.

By the way, you can set the spending for each planet independently of each other, so one world could be all manufacturing, another all research, and another 50% research 50% money.

2. In GalCiv 2 first release, you had to design every ship. If you did not design your own ships, you would fall behind as the game did not design ships for you (the sample ships were terrible). Many players liked designing cool looking ships, but many would make the mistake of adding high tech components to them so they wouldn't be available the next game they played (at least not until they unlocked those ships by researching the techs). Many players (myself included) then started a habit of design cool looking ships with no functional components added so we could get access to cool looking ships the moment that we unlocked the correct hull size. Every ship there after would be upgrades of those "templates".

The devs took notice and for the 1st expansion they added a new feature so we could save ship templates.

The AI ship designer came much later as a late patch for the final expansion. It designed combat ships for the player, 1 per hull size. You got to choose what weapons and what defenses it favored.

Now for GalCiv 3, it seems to design 1 ship per ship class (and obsoletes the previous design). Such as rangers, cutters, or avatars (these are different kinds of attack ships). They also design ships for different ship types, like scouts, survey ships, or constructors. We unfortunately don't have the means to define or edit what counts as a ship of a given class (which is what you seem to be asking for).

7. I like the turn number. I find it easier to keep track of progress when using turn numbers. For instance, if I'm not ready for war by turn 100, I need to get my but in gear. Switching turn 50 to something like January 1st, 21XX (or something like that) would only confuse me (I would have trouble figuring out how far into the game I was).