Q10: They are as follows: Thermal passive/EM passive/Grav/Geo
Q11: The expected life should you have "average" luck. Maint. life is, I believe, a combination of your engineering spaces, the overall size of your ship, and the cost of each component. There's probably a bit more to it as I'm going mostly from memory here.
Q12: Armor: Depth/width; Shields: Max strength/recharge time.
More in depth: Look at the "Armor status" menu under the F6 menu to get a visualization of what the armor looks like. The width is determined simply by the size of the ship and the depth is a player adjustable value.
So if you had a 1-10 ship taking fire from a gauss cannon (one damage per shot), the first hit will breach your armor and the second will have a 10% chance of causing internal damage. Or if you got hit with a missile with a size four warhead you'd be guaranteed to take one point of internal damage on the first hit. A fairly basic explanation, but there's tons of info on the wiki.
Shields are slightly different in that they cover the entire ship and must be taken down completely before armor takes damage. The downside, however, is that they will generally provide less overall protection per HS than armor. They also have two tech components: Their max strength and recharge rate. When researched equally, the shield will take five minutes to fully charge.
Q13: The handling rate affects the rate at which the cargo is un/loaded.
Q14: No. Grav/Geo might benefit from a passive sensor (With a bit of a nod going to thermal) in that they might be able to see potential enemies from far enough away to flee before being spotted, but an active sensor will just attract further attention to defenseless vessels. But generally speaking, if you follow a doctrine similar to mine when it comes to exploration (Lone warp capable combination vessels), you'll just eat the occasional survey vessel loss early on.
(Heh, four others posted while I was posting, putting it up as is anyways.)
Edit for Q15: I typically just hit the "Copy design" button on the bottom, make my changes, and then obsolete the old version. Designs are always considered "finished" the moment you close the window, so be careful about leaving a cargo vessel design with 100k capacity and a single engine. Civilians will build any non-obsolete freighter/cryogenic transport/luxury liner. You can temporarily obsolete certain roles if you want your civilians to focus on a specific area.