How to set up a proxy for an Android application through the per app hacking module?

Question

proxy

Hello dear experts. I immediately warn the teapot and have never been a programmer, so do not scold too much.)))
I would like to establish the following scheme:
(Server) --/traffic/---(Proxy) - - /changed traffic/- - - - ( Android application)
At the moment I got root, installed xposed, a per app hacking module, in which it is possible to enable proxy for a specific application.
Hence two questions: 1. how to
set up a proxy through per app hacking
2. Is it possible for a custom application to receive modified input information from the proxy server, and not the original one from the server directly.
Thank you very much for your attention.