moar!Fire Sphere is really weak, yeah. Funnily enough, it suffers from the same problems as Fire Magic in HoMM 3 - it is, ostensibly, the offensive magic school, but has some of the weakest offensive spells. Flaming Arrow, Call Flames, Fire Breath, and Swarm are all really underwhelming and Fireball is only so-so. The only thing Fire has going for it damage-wise is Sacrificial Flame cast by a hero with Fire Halo. Fury is a pretty wimpy unit enchant, Fire Barrier is extremely niche, IIRC Anarchy doesn't even work (or at least not on higher levels), Fire Elemental is an unimpressive summoning, and what's even the point of Fire Mastery? So what does Fire have going for it? Fire Sprite is a pretty good early summon, Fire Halo can be a useful enchant, Cloud of Ashes has its place, Warmonger is a neat late-game enchant, and Fire Storm is what it is.
Adding insult to injury, Fire's opposite, Water, is way better at direct damage spells despite the fact that these aren't even Water's focus. Ice Shards is way better than Flaming Arrow or Call Flames, Geyser and Frost Beam are both way better than Fire Breath or Swarm, Great Hail is substantially better than Fireball and can be better than Sacrificial Flame depending on the situation. Fire just does not stack up to Water, and that's not even taking into account spells like Healing Water, Liquid Form, or Flood. The humble Healing Water is one of the most useful spells in the game. Did they finally manage to wear your uber hero down to only a couple hit points? Haha whoops, they're back at full health!
I liked AoW 1's concept of opposing spheres, but in practice it didn't work out that well. Life vs Death was mostly a matter of which race you chose, Water vs Fire had a single clearly better option. The only really difficult choice was Air vs Earth.
Also, as for your 1st point, funnily enough in AoW 1 lvl 1 units are, in theory, the strongest units to use against uberheroes. The way AoW 1's mechanics work, there's always a 10% chance of a hit and a 10% chance of a miss. When a hero is pimped out with max defense, you want to start getting in as many attacks as possible. In practice that doesn't actually work out though just because of AoW 1's upkeep mechanics: mass-producing hordes of T1 units will bankrupt you very, very quickly (for reference: For the production cost of one Red Dragon, you could get roughly 14 Orc Swordsmen. However, those Orc Swordsmen would cost you 56 gold per turn. The Dragon? 10).
I maintain that unit upkeep weirdness is one of the main causes of T4 spam in AoW 1 and SM. Especially annoying because IIRC upkeep costs are hardcoded.
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