Line 1 contains only income, expenses, adjustments for the partial year only. That is, items which were received or paid during that period. Similarly, line 4 contains only deductions paid during that period. The column periods are not quarters, they are year-to-date.
These are then annualized so everything after line 6 is based on the full year (as if their AGI for the year was the amount in line 3). Nothing gets divided by 4.
The annualized self-employment tax is calculated separately in Part II.