I had this Metro Sliding Shower Door installed last week and also looked at the many installation instructions for doors I was considering. I also viewed this excellent Youtube installation video.

The answers are:

1. Yes, the installer drills all the way through the tile to attach the clips to the studs beneath. The glass is extremely heavy and one wants the most secure attachment possible.
2. There are various ways to attach the fixed glass panel to the shower base. In some cases, the installer drills holes into the into the shower base to hold the threshold in place. In my case (and in the video) the glass is held in place without drilling (I have a threshold the runs the length of the fixed panel only). The thresholds of Kohler Levity shower doors run the width of the shower and are held in place by the wall jambs on either side. I specifically did NOT want holes drilled into my cast iron shower base.

--amateur

Thanks for the info. I was assuming to go through into the studs however I watched a video online where they put floor clips in and only drilled through the tile so they wouldn't break the waterproofing. They didn't mention anything when they did the wall clips. Cheers