The selection committee understands that it is sometimes difficult to obtain commitments prior to receiving funding, so it is not required that you be entirely certain about the line-up of participating guests. However, your statement should list at least one alternative option for any off-campus participant who has not yet provided a firm advance commitment.
Your budget should include the total amount requested and an itemized budget estimate. Indicate if the event would still be viable if partial funding is granted. Please also including any funding from other sources.