The sum of investment management fees (the fees paid to the portfolio manager to invest your money and manage the fund) and administrative and other expenses (which cover all costs and expenses connected with the operation of the fund, which includes administrative fees, shareholder's registration and transfer agency fees, custody fees and all other operating expenses).
Weighted average life (WAL) of an amortizing loan or amortising bond, also called average life, is the weighted average of the times of the principal repayments: it's the average time until a dollar of principal is repaid.
Weighted average maturity (WAM) is the weighted average amount of time until the maturities on mortgages in a mortgage-backed security (MBS). This term is used more broadly to describe maturities in a portfolio of debt securities, including corporate debt and municipal bonds.