Diablo – Is the base damage of an elite monster based on the damage of the non-elite version

To answer the question posed in the initial question: Only if you had 0 intelligence and no other damage bonuses!

Base damage is simply weapon damage + any damage bonus from gear (+elemental damage is effectively "+damage" as far as the system is concerned).

The formula is roughly as follows

Base Damage =
        (weapon damage range + bonus damage from gear)
        × bonus from primary attribute^†
        × other class bonuses from skills.

Ability Damage =
        Base Damage (as above)
        × % Weapon Damage listed on the ability.

^†1 primary attribute = +1% bonus damage

Weapon speed doesn't come into play at all when calculating damage from abilities.

What this means is that weapon speed is balanced as a stat; either you deal more damage per hit (by picking a slower weapon), or you use more abilities (since weapon speed affects animation time). DPS is entirely useless as a comparison metric unless you're only auto-attacking.

Most enemy spawns are completely random.

The only types of special enemies that spawn deterministic are event bosses (events and sidequests with a "mini-boss" will always have one, although not necessarily always the same) and main-story quest-related monsters.

But since events themselves are randomized, in and of themselves they are not worth focusing on.

It is the case that some areas seem to have a higher density of elites and other high end mobs. Their spawns within an area are not deterministic per se, but if you clear the zone you will tend to find more in some areas than others. One particular area of note that fits this mold is the Vault of the Assassin in Act II.