Hi Brenda - regarding sliders not at -zero- after import, two things come to mind. One is that in the 'Details' Panel of the Develop Module - sharpening and NR do have a few default levels to begin with. I can't readily remember any other items where Lr sets a default.
The other thing is - perhaps you have an import preset enabled... that is what I do.
To see if there was an import preset - click on an image in the Library - go into the develop module - and on the left side scroll down to the History and look at the first item in the History - which should be 'Import'. If there are words following the word "Import" - it is an import preset.
I do have a user preset on import but I only set it for sharpening settings and lens corrections. The exposure is all over the charts. Is LR saying "Hey, this shot is underexposed by .5"? or something like that?
In other minor life frustrations....I've gotten myself and my files all kerfuddled with switching from lr3 to lr5 in the midst of a couple of shoots. I need to write down my work flow and follow a check list ...at least for now and until I make a good habit.