[cabmandone]

I would personally be very cautious about making any sort of surround to hide the outdoor unit. Messing with the airflow across the outdoor coil can affect both heating and cooling. Painting the outdoor unit to better blend in would by my first preference.

You mentioned flaring when you need to extend/shorten line sets. If you don't have a lot of experience in flaring copper, I'd recommend getting one and practicing a bit. A fair number of the leaks I've found on systems in the past have been at flare joints.