About the perfect party. In my opinion, a perfect party is one that can handle all set tasks using its own strengths; thus, as in almost all games, the best combination is the textbook fighter, cleric, thief, and mage. In the case of Might and Magic 8 — Knight (repairman, bulldozer - primary physical damage dealer, tank - most durable and armored), Cleric (healer, buffer), Necromancer (heavy magical artillery, potion maker), Dark Elf (traps, trading, ranged combat); for the fifth member, you can take anyone. I usually have a Dragon, but a Vampire would also complement the party well with their levitation; simply, except for cases where levitation is necessary (and there is only one such instance), a Dragon is definitely better than a Vampire because they are stronger. But a Dragon is still a cheat character, so excluding them we get:
Knight, Cleric, Dark Elf, Necromancer, and Vampire — the perfect party.