On Recumbent Trikes today, there are basically 3 ranges of gearing.
There are two main possibilities for hand position on a Trike. The first is like a "mountain bike" with the palm rotated downward, and the second is like a "bar end" on a mountain bike with the palm facing in toward the body.
One facet of Trike comfort that sometimes is overlooked is the length of the crankarms that the pedals are attached to. Think of the "circle" that the pedals make as one pedals. The longer the arms, the larger the circle. If one's legs are short, or if one has had knee or hip surgery, the circle may be bigger than the joints can accommodate. This will cause pain, and sometimes one just can't make the circle.