Early Republic; 2nd paragraph 
Right,
For the 2nd paragraph, the why (for what needs to be done), and how (suggestions) -
1st, the why:

besides the 1) excessive number of bibliographical citations in Portuguese, which I claim to be unneeded, since there is abundant literature in English dealing with the subject;
My suggestion is that (keeping the paragraph short, btw depending on the option to be chosen, even shorter), must be also fixed:

2) the truncation of the narrative, referring to fix the correlational gaps of
2.1 the beginning of the republic and the military rebellions of the 1920s, and to
2.2 the mentions about all revolts of the 1930s, and not just the communist one, 
Or 
- 2.2.1 - to maintain coherence, don' mention any (1930s) revolt specifically , in the manner suggested below

3) (Regarding the briefness of the paragraph); remove the excess of detail inferred from a source in Portuguese. Details that can be contained in other more specific articles of Wikipedia, related to the history of that period
I refer specifically to this passage  "The repression of the opposition was brutal with more than 20,000 people imprisoned, internment camps created for political prisoners in distant regions of the country, widespread torture by the government agents of repression, and censorship of the press.**" ; 
which can be summarized as suggested (see suggestion about Point 3) below 

My suggestions for How -
Regarding to: 
Point 1, use the abundant literature in English dealing with the subject, as some which I used

Point 2.1, a variation of what I had proposed:
 "Little by little, a cycle of general instability sparked by these crises undermined the regime in a such extent, through various civilian and military rebellions, that by 1930 in the wake of the murder of his running mate, it was possible for the defeated opposition presidential candidate Getúlio Vargas, supported by most of the military, lead a successful revolt." 
Or, shorter 
 "Little by little, a cycle of general instability sparked by these crises undermined the regime in a such extent, that by 1930 it was possible for the defeated opposition presidential candidate Getúlio Vargas supported by most of the military, lead a successful revolt." 

Points 2.2, 2.2.1 and 3 (bold letters)
 "Vargas and the military who supported him, were supposed to assume the power temporarily, but instead they closed the Congress, extinguished the Constitution, ruled with emergency powers and replaced the states' governors with their supporters, having defeated between 1932 and 1938, 3 major attempts to remove them from power. Being the 1935 communist one served as an excuse for they preclude elections, launching a coup d'état in 1937, making their regime a full dictatorship, with all that this entails. " 

Thus (following the justifications above), one possibility of how the entire paragraph could be:

 "Little by little, a cycle of general instability sparked by these crises undermined the regime in a such extent, that by 1930 in the wake of the murder of his running mate, it was possible for the defeated opposition presidential candidate Getúlio Vargas supported by most of the military, lead a successful revolt. Vargas and the military who supported him, were supposed to assume the power temporarily, but instead they closed the Congress, extinguished the Constitution, ruled with emergency powers and replaced the states' governors with their supporters, having defeated between 1932 and 1938, 3 major attempts to remove them from power. Being the 1935 communist one served as an excuse for they preclude elections, launching a coup d'état in 1937, making their regime a full dictatorship, with all that this entails. " 

Note that, besides Not contain the defects stated above, even With the phrase  "in the wake of the murder of his running mate, " - this possible version is by far a shorter paragraph than the present version.