Buttercream will get blurry edges as the fat will start to soak into the fondant. Use royal if you want crisp piping. Scroll takes a lot of practice, if you aren't experienced in doing it then I suggest you use a pattern.
Just add Tylose. The amount will vary based on the humidity in your area. Start sprinkling and kneading and when it no longer feels sticky and is somewhat elastic you're good to go! It's best to add the Tylose the day before you intend to use the gum paste...just "re-activate" with a bit of shortening as you use each piece.
Cut the bag and you won't have to fight with the darn tips! I use parchment bags, cut a V (start small, you can always cut it larger) then in the point of the V cut a little straight line which will give you the vein. It's a good technique to have in your bag of tricks
Your contract is between you and your customer - not the coordinator or the florist. I tell the coordinator when I will deliver the cake based upon my contract and what's best for the cake. It's your reputation on the line if something goes wrong even if you've had waivers signed off by anyone and everyone. They'll just remember that the cake wasn't good, or was melting or etc., etc... and you provided it.