Murphy's first two missions were at the jump to tingerhoff in the original game, in the remake, they are at the planet, Palan.
When starting the Righteous Fire campaign, the steltek artifact should be removed along with the gun. It's easy enough to dump it, but to make it like the original game, it should be removed with the gun.
Also, in playing the Righteous Fire campaign, I noticed at least one of the salthis spawned had the steltek gun. They aren't supposed to have that gun until the last mission (at least, the floppy disk version, the CD version just gave them fusion guns) All of the Salthis should have particle cannons only, until the last mission. I think it was the last Goodin mission before she tells you about the bounty on Menesch.
--Brandon Young