If U were the primary beneficiary of that 140,

Spouse的律師費 would only contain the 485 application for ur spouse ($500), since he/she did not need the fee for 140 unless he/she applied a different 140 and his/her 485 was based on that 140.

Generally, if the total fee is less than $3,000,written agreement is not mandatory. If it's over $3,000, written agreeement is mandatory.

If the agreement specifies a rate for any extra work, u might be charged for any additional work done.