I'm planning a trip that is 3 weeks out and after some research it looks like Hep A and Yellow fever are both recommended according to CDC. Is this commonplace to get these when visiting Morro De Sao Paulo?
You should get these vaccines before you leave the States because it takes time for them to become effective.
Also, there are vaccine shortages right now in Brazil, which would make it difficult for you to get them in this country.
there are YF vaccine shortages in some areas of the USA and Canada... availability depends on your area... see U.S. CDC webpage to find out where to get it in your area:
Morro de São Paulo (in fact, all of the state of Bahia coastline) has been included in recommended YF vaccine area for some months already (there have not been human cases, but last year there were many confirmed YF cases in monkeys in state of Bahia, showing that YF virus does circulate in the area; that is why it was included in recommended area);
in any case, talk to a doctor for assessment given your personal health and travel plans....
if indeed recommended, get YF shot at least 10 days prior to travel, as that is the minimum time for it to become effective... hep A is always a good idea as sanitation/food preparation care can be lacking in some areas (many people take the combined hep A and B vaccine as they are already in the process of getting shots, even though contagion methods are fairly different...)...