Changing DataGridView Header Cells' Text Alignment And The Font Size

You can use the ColumnHeadersDefaultCellStyle.Alignment with MiddleCenter as its value. Check the code below:

dataGridView1.ColumnHeadersDefaultCellStyle.Alignment = DataGridViewContentAlignment.MiddleCenter;

or just try this:

dgvBreakDowns.Columns[4].HeaderCell.Style.Alignment = DataGridViewContentAlignment.BottomCenter;

Try this (note I'm using Columns here and not Rows):

foreach(DataGridViewColumn col in dgvBreakDowns.Columns)
{
    col.HeaderCell.Style.Alignment = DataGridViewContentAlignment.MiddleCenter;
    col.HeaderCell.Style.Font = new Font("Arial", 12F, FontStyle.Bold, GraphicsUnit.Pixel);
}

As for deselecting the cell, try dgvBreakDowns.ClearSelection()