Water regularly for the first few weeks and continue to water in the first year during dry spells.
Your fedge will continue to grow through putting out new shoots at the top and possibly a few side shoots. As the rods thicken, they will graft at the crossing points and you might have to remove your ties if they start to cut in.
They will generally carry on to look quite "open", unless you plant them fairly tight together and leave all sideshoots on.
Willow Fedges will mainly grow at the top.
Trimming the willow fedge Your living structure can be trimmed regularly
(you can see on the picture how much growth it has put out), just like you would do with a hedge to keep it's shape.
Doing long curved fedges is not a problem,
as you can see on this picture. A large expanse of a curved fedge