Re-entering the fold of Islam

Q:

1. A person at work renounced Islam. After 6 months, through the grace of Allah, he entered into the fold of Islam again. He is now asking me what is the ruling regarding the following:

- His rewards and sins of the past

- His qadhaa salaah before renouncing Islam

- His zakaat

2. Is it also correct that his Hajj as well as his nikaah will have to be redone?

3. Is there any other masaail that is pertanant for such a person to know? 

Court marriage

Q: I was told that a divorce in court is like a talaaq. There is no need for a separate talaaq. However if you make nikaah, is that valid or does one have to separately get married in court?

Selling Islamic items

Q: I would like to start a business. Since I'm very passionate about Islam, I want to start a business with an Islamic theme to an Islamic target (I am thinking of selling Islamic books or Islamic wall arts).

My question is, is it haraam to earn money from this type of business?

P.s. It is not that I want to profit from the fact that I am Muslim, rather I feel a big passion for Islam and if there is something that I would like to spend most of my time with, then it is Islam.

The practice of joint waleemahs

Q: In today’s times, we find the practice of a joint waleemah prevalent where the expenses of the waleemah are shared between the boy’s and girl’s party. Is this a Sunnah practice? In the Hadith of Tirmizi Shareef, it is mentioned that Rasulullah (Sallallahu Alayhi Wasallam) married Hazrat Safiyyah (Radhiyallahu Anha) during a Jihaad expedition. When the waleemah was held for this nikaah, Rasulullah (Sallallahu Alayhi Wasallam) asked the Sahaabah (Radhiyallahu Anhum) to bring whatever food they had in their possession. Each Sahaabi brought whatever food he had and thereafter the food was shared by all. From this Hadith, it apparently seems that the Sahaabah (Radhiyallahu Anhum) contributed towards the waleemah of Rasulullah (Sallallahu Alayhi Wasallam). Is it possible to use this Hadith to establish the practice of a joint waleemah?