The rifle is ruined , you need to send it to me for disposal !!
Realy I highly doubt that any serious pitting occured in the several hrs that it was outside , get some good brass or copper brushes , bore brushes work well and scrub the area with WD40 , that will get the rust out and keep it from rusting anymore , it should be fine and I doubt that you will be able to feel any differance.
As for the crown , cutting the barrel back isin't needed just recut the crown and that will fix the trouble generaly no more than .020"-.050" needs to be removed depending on the ding.
On the bedding trouble , well you learned a lesson the hard way , take your mistakes and use them as tools to learn with , release agent is cheap , it may be a pain to clean up but not nearly as bad as not using enough. I conver everything that has any chance of getting bedding compound on it with release agent.