To reply your questions, primarily based on the patch notes and the official weblog:
Will they seem on the wild as shiny pokemons do?
No, solely pokemon which can be traded can get the fortunate trait.
Can all pokemon proper now be fortunate?
As it appears proper now, any pokémon that may be traded can get the fortunate trait.
Are there any variations other than the background impact?
Lucky pokémon require 50 % much less stardust to energy up than pokémon with out the fortunate trait.
Will there be a noticeable distinction when on the map?
Not relevant since fortunate pokémon do not seem within the wild.
Will a fortunate pokemon be for everybody or randomly for every consumer (like shiny)?
Lucky pokémon are a random likelihood when buying and selling, with a better likelihood for pokémon which have been in storage for some time. When a commerce triggers the Lucky trait, each pokémon obtain the trait.
Source: https://www.polygon.com/pokemon-go/2018/7/23/17602604/pokemon-go-update-lucky-pokemon and the hyperlinks inside.