Front calipers not releasing

If you lift up on the brake pedal you should be able to move the push rod away from the MC a little. If not rod might be to long as others have said.

Regarding rounding of the nuts on the hard lines are you using a flare nut wrench like this (standard not metric)
https://www.lowes.com/pd/Crescent-2...82o77uIl2YYNFLu4LVOBAv9ricLhLkf0aAvCjEALw_wcB