Premiere Pro, what actualy uses GPU acceleration

A lot of people are talking about upgrading, should I upgrade GPU/CPU etc.  In this contest I started to look for a good article on what actualy utalises GPU acceleration.  Done a load of googeling and cant answer this question so I thought I would put it out there.

Few initial questions:

Does playback with strightcuts/cross fades use GPU acceleration (if timeline is same res as footage)?

What if its mixed rez footage (i.e. resizing is needed)?

What if you resize (push in/reposition/zoom over time...)?

Do the above things use GPU acceleration in the same way for exporting as payback.

In terms of effects there are icons by effects showing whitch utilise GPU so I know this.