Posted: 26/03/2016 at 15:24
Reeds won't grow outside the liner so substitute with a grass or other plant with reed-like leaves
Have you got a planting shelf within the pond for marginals? They will overlap the edge by the end of the season. You can grow reed like plants here but avoid phragmites and anything else invasive, they may be in pots but that won't stop them.
Amphibians will just turn up if they're in the area. If you import spawn at this stage there's nothing for it to spread disease to.
I'd recommend visiting a few gardens to see what others have done. You've got plenty of time, water plants can be added through the summer