for the feat, that'll be the most difficult, to imbalance the HP cost for a chain of feat or for only one.....that'll be quite hard for this.
Compare the benefits of the whole chain and the single feat to already existing Heroic Abilities, and you will get a feel for if they should be converted as a chain or single feat.
I very much think that the Cleave -> Greater Cleave chain is a perfect Heroic Ability in its own. If you drop an opponent, you get to use a Reaction to attack the next opponent that is close enough to you.
The Maximixe Spell etc. feats also could be a single heroic ability that maxes your manipulation of Sorcery spells more potent.
As for the Midnight Defender Class, I think it's abilities are better suited as an Heroic Ability, or a Heroic Path in RQ form (as discussed earlier). They are a very iconic class for the setting, and their central abilities should be preserved.
The Wildlanders class abilities are more easily converted into making him really good at skills, as he basically is good at fighting and tracking. The RQ Wildlander profession should have large bonuses on it's skills in these areas that make the Wildlander class unique.
I do not agree with using RuneCraft as MageCraft, at least not in the form it is. You could use the spells from it as MageCraft, but you should proably remove the runes altogheter.
As for the I agree that legats should use divine magic. And spirit magic should probably one of the most common forms of magic.
But I do not think that Channelers should use Sorcery. Sorcery in RQ are a studied path, a logical approach to magic. And as such it has more in common with D&D's Wizards. Channelers should be able to use magic without training, in an intuitive way. That is more in their character.
As such I think it should be handled a bit differently.
Introduce a separate skill; Channeling. That is used to channel magic. For each x% you gain in this skill, you can "learn" (I would say use or channel) a new spell, and you use the Channeling skill to do it.
The spells available should probably be from all availble magic in the setting (and available in the RQ rules).
There is a reason that Channelers are feared by the shadow, and why the Legates try to erase them from the world.
Perhaps Channeler should not even be a profession, but a Heroic Ability that is the only way to learn the Channeler skill on which it's magic is based.