Steve I'm not sure for the error on the spacing thing as I've never observed it or better to say never checked it. Can you try it on different files and check. What is the possibility of sharing your files to check.
For the time thing, after you have done with animation wizard, select all the keys and drag them to left side with either of shift or alt button (heck I can't remember exactly which button). The whole animation time will get shorten.
This is probably because you have multiple exploded views in the current configuration.
I just had the same problem and realized that I had two different exploded views in my default configuration. Got rid of one. Worked like a charm afterwards.
There are still problems with this feature in SW 2018. If I create an exploded view of a simple hinge via a new, single configuration, I can set rotation to a certain angle. Upon exiting, I can choose "explode" or "collapse" and see the configuration exactly as I set it up.
If I choose "Animate Explode" from the right click menu in config manager, it will often generate erroneous results. Typically, the end rotation direction is the opposite direction of what it should be. Choosing the non-animated "explode" gives me the correct end position, "animate explode" does not.
The Implication here is that the Motion Study Animation Wizard will replicate these faulty results. When contacting SW about this, they told me to manually manipulate the model in Motion Study to correct the end position error. Exporting an explode to eDrawings or Visualize is a royal pain.
TLDR; Inaccurate Explode Animations is a major bug that SW has chosen to not fix in at least 5 years.