No.
I beg your pardon, but can you direct me to the train station? The governor issued the pardon just minutes before the execution. The pardon absolved him of the crime.
Certainly they might, and they can, and will, be charged with it.
In ANY state, a pardon for a conviction of a STATE prsecuted crime can only be issued by the Governor. You must petition the Governor of your state and give good reason(s) why it should be granted.
The forgiveness of a crime is called a pardon. Or amnesty.
For a pardon - write the Governor's Office.
Impeachment
Yes you can; it is usually enough to have an arrest warrant issued to be extradited.
He was charged with Rape, convicted and spent 29 years in prison, but DNA proved he did not do it and exonerated him, and he was released with a full pardon.
Pardon can be a noun -- I beg your pardon, I didn't see you sitting there. Pardon can be a verb -- The judge will not pardon his crime.
forgive
Usually right before they vacate the office.
No. You cannot be charged with a crime for which no law existed prior to your committing it. Those kinds of laws are known as Ex Post Facto laws and are prohibited by the US Constitution.