See http://www.irs.gov/pub/irs-drop/N-13-31.pdf Section 3 table for the adjusted housing allowance of 48,000 allowed for 2013.
See http://www.irs.gov/uac/2013-Inflation-Adjustments-to-Various-Tax-Benefits for the foreign earned income exclusion rises to $97,600, up from $95,100 in 2012.
Whether or not the per diem is non taxable is dependent on the facts and circumstances in your particular case.
In general, per diem payments will be taxable to the employee if any of the following are true:
No expense report is filed with the employer,
The expense report filed does not include the date, time, place, amount and business purpose of the expense,
A flat amount is given to the employee and no expense report is required, or
Per diem is paid in excess of the allowable standard federal rate.
The per diem payments listed above would be treated as wages and employment taxes are due from the employer
Even when properly not included in gross income the per diem may be part of the Form 2555 computations depending on circumstances.
"Foreign earned income for this purpose means wages, salaries, professional fees, and other compensation received for personal services you performed in a foreign country during the period for which you meet the tax home test and either the bona fide residence test or the physical presence test. It also includes noncash income (such as a home or car) and allowances or reimbursements."
"Line 23. List other foreign earned income not included on lines 19-22. You can write "Various" on the dotted lines to the left of the entry space if you have other foreign earned income from multiple sources.
Line 25. Enter the value of meals and/or lodging provided by, or on behalf of, your employer that is excludable from your income under section 119. To be excludable, the meals and lodging must have been provided for your employer's convenience and on your employer's business premises. In addition, you must have been required to accept the lodging as a condition of your employment. If you lived in a camp provided by, or on behalf of, your employer, the camp may be considered part of your employer's business premises. See Exclusion of Meals and Lodging in Pub. 54 for details."
Hope this helps to know the limits and general rules for per diem exclusion from income and that the reimbursements are used in the Form 2555 computations.
Please ask if you need more discussion or clarification.