Going from a tractor mounted boom to Hagie sts and need a little help.  Dealer has agreed to throw in a couple sets of tips.  These will be deere tips since he is a deere dealer.  The Hagie is set up on 15" spacing vs my old boom on 20"

Here are my questions

1.  What are the pros and cons of the different materials used in tip construction.  Poly, ceramic, and stainless?
2. Do I want 80 or 110 degree spray patterns for herbicide application? I assume this is related to height of boom from target and nozzle spacing?
3.  Is 10 to 12 mph a reasonable speed to expect?  I was usually in the 6-9 mph range with the tractor.
4. For those familiar with Deere tips and spraying contact herbicide, would the guardian, low-drift, or extended range be your pick?
5.  What's a good tip for spraying fungicide in late season corn?

Thank you