(2) If he pays me variable like one time Rs. 5000 another month 6,000 is this halal? Please suggest your opinion on this with valid points.
بسم الله الرحمن الرحيم
It is not lawful to take profit each month without investing ones money as partnership or muzarabah. Likewise if he gives money without fixing it then it shall also not be lawful to take it. If you want to earn profit then it shall be necessary to invest your money as partnership or muzarabah.
Allah knows Best!
Darul Uloom Deoband