Start and end times are relative to the resolution of the sequence. So, even if you could enter a time manually, it may make no difference. For example, on a 50ms sequence, if the start time was 1.00 and you enter 1.01, then there will be no change. A valid change would be 1.00 to 1.05.
You can move effects up, down, left, right by dragging or by cursor keys. To me, cursor keys are the easiest. Also, having a good timing track makes things easier because effects can be easily placed on these marks.
Feel free to suggest enhancements, but I would spend time getting to know the software in it's current state. I have used LOR, Vixen, HLS, etc, and xlights is by far the easiest to use and allows quicker sequencing. You just have to be able to adjust and forget the others sequencers that you have used.
James