Where can I find beer for Letitia?
There's an informant in Detroit and the game has an option to give her beer, but apparently beggars can be choosers and she will only take "Mahara Jah Hot Devil Ale".
Where can I find that beer and what are the advantages for giving it to her?
Solution 1:
There is a reason why Letitia was digging around a garbage can when you first see her.
You can find the beer she wants (Mahara Jah Hot Devil Ale) in those if you search in enough trash bins. There were also a few to be grabbed in the Milwaukee plant in the first mission.
As for why anyone would want to throw away unopened beer, I have no clue, except maybe that perhaps she has horrible taste in beer and that stuff tastes horrible.
When you give her 4 beers, she gives you the code to Seurat's stash by the basketball court. If you knock her out, you'll find the pocket secretary on her with those codes. (and all your money back)