Hello, FNG here.

Well, I personally use maps and draw elevation lines when necessary. I add notation to indicate whether or not the elevated area is a hill, a ridge, or some other sort of feature.

Hills and elevation can be tricky. For instance, the British at Waterloo were on a ridge that gave them a significant tactical advantage. But the advantage it gave them was that it shielded them from the eyes of the French gunners. It doesn't take much rise to do that. A few meters over a mile at most. The same ridge wouldn't necessarily fatigue the approaching French as they walked up it - maybe a bit, but it is difficult to quantify an advantage like that. Then again, American Kriegspiel (from 1880-something) says that troops who march up a slight incline before shooting suffer a serious reduction in accuracy, something like 15%-20%. Which conveniently is about -1 on a 1d6. I guess my point is that a significant "hill" might only be about 6' tall.

Another example is the main Union line at Gettysburg. The elevated terrain on the Union line was really a very gentle slope - once again, a rise of only a few meters. But it protected them from the war's largest artillery bombardment and hid the strength of the Union line from the Confederates. The Confederate position at Antietam is another example. The elevated terrain there protected them from the Union's artillery advantage.

Other than providing your artillery and your officers with an extended LOS, I think that the real advantage of relief is that, on the defense, it shields your positions from the enemies LOS and forces the attacker to guess where your line is weak. This is extremely difficult to model in traditional wargames because people like to plop all of their models down on the table at once.

The other issue with physically modeling hills in 2mm and 3mm is that they tend to overwhelm the models. I spent a year or so trying to figure out how to get around that in 3mm before I saw the light and moved on to maps. Some of my struggles are detailed at my old 3mm blog, if you are interested: 1809in3mm.blogspot.com

Right you are, O.S RE: "FNG". I figured it was better to call fire in on myself than have others do it.

That craft foam could be useful, agreed.

As for speed painting, I don't have much of a primer on it. It's really pretty easy though. I"m at work, but here's a quick breakdown of what I do.

1: Always print in grey plastic.
2: Paint the ground first.
3: After the ground dries, paint the figures in their basic coat color.
4: After that dries, paint a stroke of the secondary color (if any) down the front of the front rank of troops.
5: Add pink dots for faces.
6: Decide if the soldiers hats can be characterized as "bright" or "dark." This is entirely subjective. The French are bright. The Prussians and Russians are dark. The Austrians and British are in-between. Paint the tops of "bright" units with their pompom color or the color of their elite companies. Paint dark colored units light grey (never use black at this scale, or even dark grey. It tends to overwhelm the figures). If the units are inbetween, paint their hats grey, plus a small dot of the high contrast color on the hat, on the side or the front.

Individually this won't look like much, but combined it creates the look of a unit.

When I want to focus on painting formations and mass, then:
1: Paint the base green.
2: Paint figures the main coat color
3: Dry brush or draw one line of secondary color down from of the figures.
4: Dry brush the top of the figures either light grey, a pompom color, or steel/silver (to show bayonets).

I hope this helps!
Also, the advice is for the infantry.

Quick take away is, you can really paint out a lot of these in one sitting without too much work. If you want to be as fast as possible use the models with the flags modeled onto them already (although I personally prefer printing out and gluing flags onto the flagless models, it adds a lot more time to the process).