@EF
The AI values its miners relatively high, at last check. Certainly not as much as their flagship, or even their econ treaties, but that's a bit much to pay for a miner. Further, as mines flip relatively easily, it's only the planets that matter. But interesting from the viewpoint of shutting down an avenue, albeit a small one, of their production.
Anomalies also regenerate in late DA (1.7x or 1.8x, I forget). The "survey ship gets more hp" talk is about the anomalies that it runs into that give it bonus hp. The "upgrading survey ship" talk is about taking your flagship, or a few small survey ships with several hp bonuses due to anomalies, and upgrading the ship itself (not the design, as someone else seemed to have suggested) to a different design, i.e. a fighter or even an armed survey ship, as the extra hp makes it that much more effective in combat.
You don't need any techs to build colony ships, EF. You can design your own cargo/small ship (without miniaturization, you're not hitting 20 space on a tiny) with no techs researched and slap a colony module on it. Further, the prebuilt ships are arguably useless when compared to ships the player can design, if only because they're largely inflexible. The autodesigner helps with this somewhat, but is to my knowledge only for armed ships, so it's not going to help you with colony ship or constructor design, among others.
While you may not have sensors researched, any ship can auto explore, if memory serves, which is really all a scout's purpose is.
As for the talk of upgrading the miner into a colony ship-the only time you -don't- want to do this immediately is when you're using the Thalan tech tree, as the extra industry the mined asteroids provide help make up for your initial lack of factories.