Hospitality (teranga) is a major tenet of Senegalese culture. As a result of this, being invited to somebody’s home is rare, unless you suggest it in some sort of way, such as “let’s have dinner together sometime”.
In the capital Dakar, everything moves quickly. Don’t pause for too long otherwise you will be approached by street vendors or shop owners who want to take you to their shops. Pedestrians also do not have the right of way.
To avoid being approached constantly, learn to say (in French or in Wolof) that you live and work in Dakar.
Women should avoid travelling alone, as men will constantly come up to you and ask if you’re married. If this does happen, per chance, just tell them that you already have a husband.
Beggars are not uncommon, however, despite there being many in need, there are also lots of scams. Give money to children, and not adults, unless you see that they are really in a bad situation.
Both Christian and Muslim holidays are observed.

https://www.cia.gov/library/publications/the-world-factbook/geos/sg.html (Majority of information)
http://www.ansd.sn/index.php?option=com_ansd&view=theme&id=9 (City population data)
Wolfram|Alpha (Currency exchange data)
Information accurate to best of ability as of 29 November 2016