Réponse:

1. Louis Armstrong statue was placed in this park because it is a iconic location for the history of Louisiana. This place is where slaves were allowed to dance, sing, and in any other ways, have good social gatherings during though times for them. It is also where Jazz started getting popular thanks to the multiple people who went there to participate, and the others who just enjoyed. Even if those gatherings were shut down for good in 1851, this area was still representing gatherings and rare good moments for slaves through music, especially Jazz, so it was without any doubts that if someone were to represent this park, it would be Louis Armstrong, a pillar of Jazz music and its movement.

2. The different groups of people who used to come to Congo Square were mostly enslaved Africans, but also "domestic workers", "free people of color", and "outsiders", as said line 21

J'espère que ça a aidé, bonne chance :)