Question on IWC 3777 14 Petite Prince Chrono service and accuracy

Hello,
I'm about to purchase an IWC 377714 pilot chronograph Petite Prince and have some questions, if members here can help me clarify.
I read the caliber 79320 is reliable and robust, but suggest the watch to test water proofing every year and recommend service every 3 years, which seems to be unusually frequent. I fear the cost of service is high, and frequent servicing decreases the joy of ownership.
Should I expect the accuracy of this watch to be -4/+6 out of the box ? If I expect it to run +2, is that to much to ask?
In the date /day change over, is this a gradual process spanning 2-3 hours like my older IWC UTC 3251, or is it a click jump instant change?
Thank you in advance for your time.
Love this forum. Rollee

I hope you go ahead and purchase the 377714 Pilot as it's a beautiful watch.
Please see my answers in BOLD below