Haproxy reload - production ready

I am currently using haproxy and we need to make it production ready.
I have few questions.

Currently we are maintaining single haproxy file. Having one frontened , some acl rules and multiple backends. I want to split blackened into multiple files. Is it possible, we can selectively include blackened? Or we always need to have backend , if we have entry in acl.

Is there a good way to reload the config files, if we add or modify a particular blackened file only.

What about running multiple instances of same haproxy. And respective application maintain their own config and reload them independent. Is it a good practice?

Request you advice on this.