Newbie question I know, but how can I fill with a two-color gradient... or must a gradient be from the fill-color in the current object, to the fill-color of the underlying object?

BTW, how do I get the gradient-handle to show in an object (so I can drag where the gradient starts and stops, as well as it's direction)?

Objects are independent from one another, so you can style one object with a gradient and it won't depend on what other objects are styled with. If you have transparency you can have different effects where you can see the lower object through the top one, but still their styles are independent.

There is the Gradient tool you can choose from the toolbar (Ctrl + F1), when it's selected your mouse pointer will change to show you what tool is active, then just start dragging over an object and it will turn the solid color into the gradient from that color to transparency. After that you'll notice the gradient handles so you can move them, add new ones and change the color of each stop.

One might infer, from your question in your other topic (viewtopic.php?f=5&t=10556) that you're thinking you need 2 overlapping objects, the top one partially transparent, to achieve a 2 color gradient. But once you apply a gradient, you can put one color on one end, and another color on the other end. (And from there, as many more colors as gradient stops, if you want more.) So you might only need one object. But this inference might be incorrect...

I usually use the Fill and Stroke dialog to apply the gradient, then switch to the Gradient tool, to edit the gradient. But you can also leave the object unfilled, engage the Gradient tool, and draw the gradient by dragging the mouse.