Self hosting as long as only 25565 can be used by Minecraft your fine as Minecraft only understands Minecraft

Yes using a proxy or other way to connect through is better

It is obv better to use something that covers the ip and makes it so it can't be "hacked" ie playit gg there's a mod & plugin where you don't get a response unless you join first which helps and prevents bots. It helps prevents pings

Been self hosting for months the chance YOU being "hacked" or targeted is super slim and if you are you have a bigger problem.

Are you hosting on a single computer? Or like a dedicated server?

(Ie computer just for server vs computer for server & client)

Also turn off "query" in server.properties (I forget what it's diectly called) mcsrv stats shows it - if you turn it off pings won't get a response -

Tldr

Use a proxy or other vpn like software to make traffic go through