The total of both of these single allowances is always more than the "with dependent" allowance.If a military member marries another military member and they have children, one member will receive the "with dependent" rate, and the other member will receive the "single" rate.
The dinner or mess dress uniform is equivalent to civilian "black tie" requirements.
The choice to attend the wedding in uniform as a military guest is optional.
If you are overseas and marrying a foreign national, it's a different story.
There are multiple forms to complete; you must obtain counseling and your commander's permission (which is rarely withheld without very good reason); your spouse must undergo a security background check and pass a medical examination.
You don't need advanced permission and there is no special military paperwork to fill out before the marriage.