The front axles are not an issue unless you try to roll Norcal SS style or even close to that. If you did go that low, the upper ball joint will be a major issue. DJM upper arm would be a must.
lowering rear 1.5 is fine your compressor will still kick in. I posted the new air ride bags which bolt right in for the rears and a member bought them and will be testing them out. Check the rear bag section