if you mean using the stash version of git, use git fetch origin. (or whatever your remote name is) will bring the changes from the remote repo into yours, into a seperate remotes/origin spot, so wont override any of your pending changes (use git merge to do that).
there is not a super easy way to see the changes, other than to do a merge, then git diff before comitting (assuming it is not just a fast forward merge, which does not require a commit.). you can use git reset to then go back to the pre merge state, or int the case of a fast forward merge, you'd need to point the branch back at the old sha.
backup before trying any of this, and make sure you have no uncommitted local changes!