Dealing with Sherwin Williams solid color stain

My deck was stained about 2 years ago with Sherwin Wms solid color stain.  Not totally sure what was on the deck prior to this (I think it was a semi-transparent or transparent stain).  Of course, the new stain is now peeling and it appears (after reading through various other posts) that most strippers won't work on a solid color stain.  So - I'm interested in learning:

1). Is there a product that will effectively remove the current solid-color stain?

2). I've already sanded off any loose stain.  Is it OK to restain the deck with the same solid color stain?

3).  If I restain with the same product, are there any issues if I choose to go with a darker color?  The current stain is a light gray.  I would go with a darker color.

Thanks!