It depends on how many wall levels you still need. A TH18 village with all 325 walls at level 18 needs 3.25 billion gold and elixir for level 19. Raiding villages with at least 1M of each, that is around 1,500 raids, or roughly 20 hours of searching and attacking.

1M of each is usually fastest. A 2M village brings twice the loot, but there are far fewer of them, so the search takes several times longer on every raid. The calculator compares every threshold side by side for your walls.

Yes. From level 5 every wall upgrade can be paid with gold or elixir at the same price, so both resources from a raid go into walls.

The events with 20 Electro Dragons, 50 Lavaloons and similar armies run from Town Hall 10 up. The calculator covers TH10 to TH18, with each hall's wall count, max wall level and storage capacity.

A resource fest boosts the loot in every village, usually to 200% or 300%, so a good village holds about 2M or 2.5M of each. You raid it with a normal army: a 5 to 10 second search, a 45 second to one minute attack, and out at 50%. Because the attack is long and the search short, it usually pays to search for more than the base. The calculator keeps the two events and their assumptions separate.

Yes. Every won raid counts for Conqueror, and the defenses you destroy count for Humiliator, Firefighter, Union Buster, Mortar Mauler and the other battle achievements. Load your village and the calculator shows the stars your raids reach and the gems they pay.