To keep the handling the same, whatever you drop the back by drop the front the same. 10mm at the front is not enough, it will handle like an 80's cruiser and run wide on the exit of corners.
I did this when I fitted a 25mm lowering kit. All of my experience was telling me to lower the front by the same amount, but I too had read this 10mm advice thing so thought there might be something in it. WRONG!!
Saddle wise, have a look to see if there are any coach builders/car upholsterers in your area, then find out if they have an apprentice that might be able to do a small job for some beer money. Got to be cheaper than saddle specialist!