I have a split AC system with the Outdoor unit just across the wall
where the indoor unit is fixed. The AC system comes with pipes that
are 3 meters long - whereas the actual length required is less than
1.5 meters.

Right now the pipes are coiled together and tied to the outdoor unit.
When the AC is running, the pipes shake and vibrate a lot. I am
worried if it might affect the connections to the outdoor unit. Also
don't lengthy tubing reduce the efficiency of the AC?

Is is possible to cut and shorten the piping so that we don't have to
coil the same. I have seen many places where the pipes are short and
neatly clamped to the wall. I've read that the pipes need to be flared
at the end using some special tool after they are cut.

What is the best practice in such situations? Please let me know if
its ok to shorten the pipes and clamp them to the wall after proper
insulation.

Thanks

Vijay