Source: US Census. The median household income in the US is $50,502. This is some extremely useful data given that it is exploring over 114 million US households. If you want to know how most Americans are living this is a good figure to base your assumptions.
The myth that you have to wait 30 minutes or even an hour until you can swim after eating has been conventional wisdom for some time. The simple fact is, however, that swimming on a full stomach does not significantly impact your ability to swim.
Go to bed as early as possible beginning days before your swim meet, especially if you are getting up early. If you go to bed at midnight every night for a week and get 5 hours of sleep every night for a week, getting 10 hours of sleep the night before is not going to help you.