Yes they will spawn, they are the same sp.
There are various different spawning trigggers, cold water change etc but common BN's are the guppies of the plec world they shouldn't need much prompting, in fact most people success with spawning plecs in general comes from just leaving them to it rather than intefering with them a lot.
Condition them (nice high protein diet for a little while) and then let nature take its course.
Not sure about the pep question but i can't imagine it would be any different