Stock recovery and upgrading Lollipop with future OTAs after rooting topic

Hello everyone,

I'm back to a nexus 6 after a very short stint with a 6+.
A little background for my questions: This is the very first time that I rooted a phone. I'm rooting to only install these 3 apps:
adaway
titanium backup
greenify

I do not plan on using any custom ROMs or kernels.
I see from all the guides and tutorials that people also create a custom recovery whenever they root. I haven't done that yet and wasn't sure if I had to. I would like to maintain the stock recovery that I have currently so that I can go back to stock if I unRoot. My questions are:

1. Am I wrong in thinking that I can still use the stock recovery if I unRoot?
2. When a new OTA comes out and I flash it (since I'm rooted an no longer can install them automatically), will that also upgrade my still stock recovery properly?
3. Following up on the previous question, when I upgrade manually because I'm rooted, would that be a fresh install where I have to go in and configure things the way I like them again (system settings, apps and their settings, root the phone again, etc)?

Thanks in advance!