For your first question, Lectora doesn’t have a corner radius readout, sadly. If you don’t want to get into creating the pill-shaped object with CSS where you can explicitly set this numerically, then my suggestion is that you copy & paste the object you have, and then resize the length/height to preserve the radius of the corner rounding.
To your second question, you can modify the gradient of the coloring by going into the gradient menu, and clicking More Gradients…
From that menu, you can modify the Gradient Stops to adjust where color gradient begins and ends. If you’ve used graphic design software before, this may be familiar to you. If not, then you may have to play around with it a little before you figure out how to change the slider(s) to get it the way that you want.
Personally, I’ve found it easier to define gradients through CSS, but that’s just because it’s the tool I’m most familiar with. I know some people for whom Lectora’s slider is easier. That is my favorite thing about Lectora though, if you find any of its built-in tools insufficient, you can always work around it through external means!