I forgot to mention this earlier but Infinity is a not time magic. What it does is it essentially removes the upkeep of any spells she uses. For example she can light a magical campfire and the fire will keep burning forever without any need for additional fuel. The spell that Merlin used to stop her own time was not Infinity but something different, presumably similar to the spell she tried to use to stop Meliodas's time when he was in the cocoon. The problem with stopping time is that according to Greyroad, it takes a large amount of magic to twist the laws of the world, which means it's not possible to keep such a spell going for very long. You'd quickly run out of magic and then it would come undone. That's where Infinity comes in, as it meant Merlin only had to cast the spell once to keep her time stopped forever.
You are making a big deal about creation but that's actually a very basic use of magic in the NnT-verse. Annihilation is when matter is converted into energy, meaning the the opposite process of creation is just magical energy being converted into matter. This happens when Escanor generates a miniature sun in his hand, for example. He takes magical energy from within his body and transforms it into physical matter, which appears to have mass and a solid form judging by that time he used one to blast Estarossa away. Tristan forming his light and dark magic into small orbs and such is also the same phenomenon. Almost every character with some kind of elemental magic, think Jericho, Pellegarde, Tarmiel and what have you, is capable of creation so it's not particularly noteworthy. Ironically the one exception seems to be the Creation magic of the giants since it's specifically about manipulating earth and rocks rather than creating them out of thin air like how most elemental magics work.
Annihilation is much rarer than creation because, as far as we know, it only happens when light and dark magic cancel each other out. What makes the Annihilation technique special is that two opposite magics cancelling each other out creates an explosion with more force than just the individual attacks on their own. Nakaba probably got the idea for the technique from the concept of using antimatter as a weapon, which is based on the fact that matter and antimatter annihilating each other is a more efficient way to produce energy than even nuclear reactions, meaning antimatter bombs would be much more destructive than nukes of the same weight. As far as Tristan is concerned, Annihilation is also convenient in the sense that it produces an explosion of raw energy, which is not affected by any resistance to light and/or dark magic like what the Testament Beast had. In a nutshell, Annihilation is a non-elemental attack that hits harder than other attacks of the same size. I don't think there's any deeper meaning to it.
The power absorption has a loose resemblance to Snatch but that idea falls apart when you start considering things like Lancelot's ability to fire off homing laser beams, creating barriers and forming weapons out of energy. I think Hazy Moon is something totally different, just like how I don't expect Tristan's Nova to have anything to do with his parents' magics. He's already got his father's demon mode and Full Counter along with his mother's healing prowess. That's more than enough given that you don't want the new main characters to just be a repeat of the previous ones. Lancelot has his mother's heart-reading and I think he may have inherited some of Ban's physical stats as well. The chapter in which Lancelot beat up Arthur with his bare hands was titled Hyperion, which could have been a reference to one of Nakaba's previous manga in which a character (that looked very similar to Elaine) had a condition called a Hyperion Constitution that caused her muscles to be exceptionally dense, making her body abnormally tough and strong. Lancelot having inherited a similar constitution from Ban as a result of Purgatory somehow altering the latter's body could explain Lancelot's ridiculously high physical stats. You wouldn't normally expect the son of a dainty fairy and an ordinary human to be so durable. He didn't even take any damage when he got sucker punched by Chaos emerging from Arthur's arm, the same monster that pushed Meliodas back immediately afterwards.
