Forcast would be for spells that while memorized give the character an additional cantrip. I would limit to classes that prepare spells: wizards, magus, cleric, paladin, etc; and keep them away from spontanious casters.
Addendum would gives spells an additional effect when cast using a longer action than normal: a swift action increased to a standard action, a standard action increased to full round, etc.
Cypher could be that after it is cast, choose a weapon within short range. For the next minute, that user of that weapon may use that spell as a Swift action spell-like ability after dealing damage with the weapon.
Haunt would be similar, but choose a target within short range. If that target dies while within range, the caster may use the spell as an immediate action spell-like ability.
Replicate could allow the caster to sacrifice additional spell slots of the same or higher spell level to effectively recast the spell as part of the same action.
Radiance and Overload are the last abilities primarily for spells, I don't know how to make them work in a manner that fits PF mechanics and the original feel.