Granite and water damage
Granite can be removed without it being damaged in 90% of all cases.  We would need to see pictures before helping out with that.  If granite is installed right it should be held in pace by a couple of wood blocks underneath in the corners - ensuring it can be moved if there is work that needs to be done.  If it is installed like this it literally takes a few mins to disconnect it from counters.  If it is glued to plywood or the cabinets it is much harder but still doable.

Notes:


Grout should never be used at the corner of a counter/backsplash.  Even if you had a tile counter you would ALWAYS caulk where the counter hits the wall.  
All counters are sloped.  My kitchen counter reads true on a level.  But if I spill water it might take a day but it will all end up on the left side.  Sounds like yours are sloped back... which isn't good but not life altering.
You should check for water damage behind your cabinets.  You can easily make a couple of cuts and take a peak and no one will ever notice.  
If your walls are wet, they will dry given you cut out the leaking.  Most water damage is no big deal.  Mold and other fungi will die quickly without water.  It depends on the severity of the issue.  But temporary water damage is not usually a precursor to a kitchen gut.