Clash-of-clans – the maximum distance between 2 AD so I can kill both with 1 earthquake and 4 lightning

tl:dr Yes it is possible, but they have different town hall level requirements and costs, so you have to have a high level village with substantial resources to purchase both.

Barbarian King - Available at Town Hall level 7, and costs 10k Dark Elixir. This means you can potentially purchase him without spending money if you build and completely fill the Dark Elixir Storage which is also first available to you at TH level 7. Note that you can do this by spending gems, or by raiding - but you don't get a Dark Elixir "mine" till TH level 8. (It's painfully slow, so don't hold your breath waiting for it).

Archer Queen - Available at Town Hall level 9, and costs 40k Dark Elixir. This is substantially more than what your early Dark Elixir Storage can hold, so effectively you'll have a hard time getting her early on without spending gems. If you are very patient, or a very successful end game raider, then you may eventually get her without spending money.

The amount of trophies you earn is not directly relative to the percentage of destruction. It depends on how many stars you earn. ( Read the bold text below )

According to the Clash of Clans wiki, "Raids" article:

For each star that you earn, you receive one-third of the available Trophies. This means that destroying your opponent's Town Hall gives you an automatic victory. Also it is impossible to get more than one star without destroying the Town Hall. Failure to get any stars means a loss, causing you to lose Trophies.

So for example, let's assume available trophy for a battle is 30. If you destroy the Town Hall and 50% of your opponent's base you will receive 20 trophies, and if you keep destroying it until 90%, you still will get 20 trophies.