Thanks for all the thorough responses. Think I need to now sit and do some envisioning.So you can choose to rock the walls in your pond OR You can leave them bare - mostly personal preference. You have a narrow pond to work with - I think I'd go with no rocks on the side to allow for more water volume.
You do NOT want large rocks in the bottom of the pond - they can trap debris and cause problems down the road. But a shallow gravel bottom will give bacteria more surface area to colonize. It's another one of those "love it or hate it" concepts in pond building - your choice really.
As for the edging - all of those are fine. The ONLY thing you need to worry about is keeping the liner above water level. They don't do the best job of illustrating that - you want several inches of liner above the water level - too close to level and you're risking wicking or plants breeching the edge and pushing down the liner. (Keep reading to find out how I know that!) I'm not a fan of cementing anything in place. First because I have no idea how to do it, but secondly because you'll find you want to move things around or make a few changes here and there. Once you've cemented rocks in place you're kind of stuck. (haha!) Now if you're looking for a formal pond then the capping and cement makes sense.
The one thing they don't illustrate is that you want to fold the excess liner (and you DO want excess) down behind the rocks on the land side. Keeping that excess liner available could be a life saver later. Ponds settle, rocks settle, dirt settles... and then you find yourself with a liner that's too short. We just had 2/3 of our ten year old pond re-edged to get the liner back up where it needed to be. No additional liner needed - they just unfolded what we had concealed behind the rocks. You then push and pack soil up behind the liner to hold it in place, plant or mulch up to the rock and you'll never know the liner is there. The Ponddigger illustrates that concept very well in his video on various edging approaches.