Slitherine

After playing quite a bit now, I can't for the life of me figure out how to:
1) Upgrade a unit to next higher class of unit; I see in the manual that it is possible, but have never found the option in game--could someone enlighten me?

2) How do I destroy an enemy shipyard? I can't seem to do it with land or sea units...any ideas?

Hi 76mm,
ad1) you can upgrade the unit in builders which are specialized in the upgraded unit type. For example you have Warriors unit (basic barbarian unit type) and you want to upgrade to axemen. You need to get the Warriors unit to a city which is specialized in axemen (or even axemen elite). To specialize city in building specific unit types, you need to use the action "change specialization" of city.
ad2) shipyard cannot be destroyed but you can capture it once you capture all enemy tiles to which the shipyard can be "bound" to. Once you capture it you can sell it.

Any questions, please ask.

OK, another basic question, even though I've played enough that I should know by now: for my troops to benefit from the protection of a city or defensive wall, do I need to "load" them into the structure, or just move them into the tile?

For all the defensive structures (stockade, palisade or city walls of cities or outside forts and defensive walls) you need to be IN the facility.

But to be IN it, does that mean to be in the tile, or to be LOADED in the structure?

In means to be loaded in the structure:)

Doh, I guess that explains why my defenders have been getting slaughtered. Sorry guys!

Another dumb question: is there any visual indication that a unit has been loaded? I tried to load a couple of units into a defensive wall, and the "Load" button remains highlighted, and I don't see any indication that they have been loaded?

You should see the "shield" with helmet icon above every time where unit is loaded into city/building

OK, but I just realized that clicking on a unit and then clicking on the "Load" icon down below has no effect--I have to select the unit, then click on it again, at which point I receive a message asking if I want to load the unit into the wall. Is that WAD?

The second time you're clicking on the highlighted destination circle.

Yes, it is by design. The point is to prevent player to do it accidentaly (which was happening quite a lot)

Sorry, I don't understand...when I select a unit, and then click on the "Load" icon, I have to go back to the unit, select it again, and then click another pop up to confirm that I want the unit to enter the structure.

Why couldn't I get the confirmation pop up when I click the Load icon, rather than having to select the unit again? With the confirmation how could happen accidentally?

You can load the unit to other map items around, that is why you have to confirm to which you want to load it.

If you start using default actions, you will understand how can this accidentally happen. Basically there is pretty much no reason to learn any shortcuts or use the buttons in game at all. You can do everything on the map using default actions and alternative default actions.
Please watch this video and it will explain it to you. The link already points to the exact part of the video where it is explained

example, you may be able to load to a city, another wall, a fort, a boat in the harbor, wagon, if they're also in the hex or nearby