Speaking ill of the sahaba

Assalamo alaikum Mufti sb.

The Ahle Bidat Barelvis accuse Maulana Rasheed Ahmad Gangohi of writing that a person who Nauzubillah abuses the Sahaba is a Faasiq , and this act does not expel him from the fold of Ahle Sunnat Wal Jamaat or Islam.

My first question : Is this true that Maulana Gangohi wrote this?

Second question : What is the correct ruling of this matter i.e the hukm on a person who abuses the Sahaba ?

Third question: We as Sunni Deobandi Muslims have respect and love for all the Sahaba , but we also know that some Sahaba who accepted Islam later on were lower in rank than those who became Muslims very early on.
Examples include Hazrat Muawiya bin Abu Sufyan , Hazrat Khalid bin Waleed , Hazrat Abu Sufyan etc.
What is the ruling of a person who abuses these Sahaba specifically?