#1 your logic is flawed. We do not need complete removal of tactics, so if it's too good, lower the mana gained, not remove it completely.
Actually, I'd tend to agree with preventing the casting of Cull the Weak on summoned units. The ability to gain 130 or so mana every battle by summoning a bunch of skeletons and culling them is a little ridiculous. I don't mind the ability to cull the single-unit summons where you aren't going to do much better than break even on the spell cost as much. Perhaps Cull the Weak shouldn't grant mana when used on summoned units, or should grant no more than the amount of mana it took to summon the unit when used on summoned creatures. In my opinion, the current form of Cull the Weak is fine for use on trained units and tamed creatures or (semi)irreplaceable summons (e.g. Sand Golems) because there's an obvious cost to doing so, but it's silly to be able to summon things tactically and recover most of the spell cost by culling them before the battle ends, or summon a horde of Skeletons and have more mana coming out of the battle than you had when you went into it. It's not an exploit I use, but it is one I think is a bit too ridiculous.
#7 I disagree, depending on the shard 200 mana is very hurtful compared to losing it forever.
Personally, I don't think that Consume Shard is worth using under most circumstances anyways. But I tend to plan for longer games anyways, and I like having magic be as powerful as possible, so trading magic enhancement for mana isn't that appealing to me. Besides which, I tend to have plenty of mana without destroying shards.
#5 Removing Beastlord and merging it to a hunter chance or ability would work better. I agree it's kinda silly atm.
I disagree with removing Beastlord, as it's a more enjoyable summoner-style magic user than the Summoner profession is (in my opinion). I would not completely disagree with nerfing it to only be able to tame equal or lower level monsters, increasing the mana cost, or making Tame easier to resist, but I wouldn't want Beastlord removed. As for reducing the experience gain for taming creatures as opposed to killing them: maybe, but I tend to find it fairly difficult to level a reasonable number of heroes up anyways, and most beasts will only take you so far into the game. Similarly, I agree that Hunter needs something, but I don't think that merging it and Beastlord is really that good of an idea even if Beastlord gets knocked back a little.
#2 Delin should be powerful During those turns. If he lacks, buff him during those turns, and leave his "turn timer", it makes him different and more interesting than the regular summons.
From the XML, Summon Delin is only active for three turns and costs 500 mana, takes two turns to cast, and can only be cast in battle. Even if Delin is extraordinarily powerful, I don't see how he's better than ~12 Blizzards for the same mana cost (and on a good damage mage, 12 Blizzards is essentially 12 armies destroyed). Moreover, even were the mana cost something more reasonable, he'd have to be truly exceptional to do something particularly worthwhile in the only three turns he's on the field. It's true he can probably kill three units in those three turns, or get off one fireball and kill a couple of units, but by the same token I could have spent far less mana casting Blizzard and killed the entire army outright. I could see Delin perhaps being worthwhile as a summonable superchampion, although then you'd need to revise the Fire side of the summoning tree, but as he stands I really don't see any reason to use him over casting Fireballs or Blizzards unless you really, really need a tank that's going to disappear three turns down the road. However, this is all based on looking at the XML, as I don't particularly care for the way in which summoning is handled in FE:LH, so I rarely use it, and I don't think I've ever developed it all the way to either end of the summoning branch of the Mage tree.
3) Don't make Maul on prone units a 100% kill regardless of hit points. I don't mind the exact mechanism, I believe there is at least one mod which does this.
I would like for there to be a fixed cap on the number of times Maul can hit. I can see a bear getting off a few attacks before everyone else in the area reacts, and I could understand initiative penalties or applying the 'Dazed' effect to mauled units, but I can't understand a whole army standing around watching as a bear makes 5-10 attacks in a row on a single unit. I would say that capping the number of attacks to four or five would be reasonable - it's still powerful, but it's not as ridiculous as some of the attack strings can be currently. That, or I'd make it into an active ability so that even if you can use it to kill off a prone unit, you can't use Maul over and over again to repeatedly take down things which ought to be tough using just a single bear cub and a few accuracy bonuses.