What to expect following major update

[Harry Putnam <reader@newsguy.com>]

Running wheezy

My updates were held up for a few days because of a problem involving
backuppc not uninstalling properly... now solved.

So now I've ran the update gui. During this update 187 pkgs were
involved.  One of them was gcc-4.6.  So I now have 4.5 and 4.6
installed.

I noticed that a new grub.cfg was installed, even though boot was not
mounted. 

Another thing that happened is that /etc/resolv.conf was overwritten
which took me offline with no ability to resolve.

So, three things:
1) Do I need to do anything special about the upgrade
   in compiler?

2) Should it be considered a bug that grub files are written when boot
   is not mounted.  Seems like if the routine notices (which it does)
   that those files are absent, should there not be further code to
   check for boot being mounted?
   It seems it should not be possible for `/boot/grub' to be created
   on an empty boot.  Not during an update.
   
3) About etc resolv.conf being rendered useless during update: That
   two seems like it should be bug 

   I pulled out an old backup with the right stuff in it and overwrote
   /etc/resolv.conf. I then proceeded to make the file imutable with
   chattr -i.

   Am I likely to run into problems with /etc/resolv.conf set immutable?