Thanks for the IPL settings. It would be more helpful if you had before pictures of the "thinned" hair areas. In general, IPL can affect the hair in a treated area. Light energy can "bleed" into the non-primary treatment zone. But the wavelengths you mentioned are not used for hair...
Benzoyl peroxide, depending on the strength, can dry up the skin. I would wait till the IPL treatment redness subsides before using BP.Best, Dr. Karamanoukian Los Angeles
The flushing/blushing on your face might be an indicator that you are suffering from Rosacea. Without pictures is difficult to make that assessment. Consider a consultation with your dermatologist/facial/plastic surgeon. A series of treatments with the Lumenis IPL has been effective in my hands...