I really like the fact that you do a Type 4 review too. This set is a bonanza for that format. Maybe the best ever! Let me ask really fast, if you play maelstrom angel, you still get to play the extra spell thanks to its ability, right?
It depends entirely on the house rules you use, as the ACC Rule wasn't part of the initial outline of Type 4. It came about as a suggestion after the format got popular. Some people play with a rule that says "If it didn't cost you any mana to play it, it doesn't count as your spell for the turn." This would allow things like Spelljacked cards and this to be free, as well as cost reduced like Convoke and Affinity if you met the conditions.
I haven't played in forever, but my group used to use the following rule: "If the card uses the phrase 'rather than pay,' then as long as you pay that other cost, it's free." This allows things like Bringers from 5D to be free and allows Fist of Suns and North Star to give you extra spells, but wouldn't make the cards off the Angel free. It's the most literal translation of ACC, and the wording that cards such as Force of Will and Misdirection use.
And then some don't play with any ACC rule at all.