(2) And after reciting what should we do?
(3) Can reciting it may have some negative effects?
بسم الله الرحمن الرحيم
(1) You may read ‘Manzil’ which contains Quranic verses in order to protect yourself against demon etc. You should read it daily in the morning and evening. If it is difficult, you may read it once a day any time. Keep on reading it until you don’t achieve your goal, rather if you read it permanently then it is far better.
(2) Just reading Manzil is cause of many blessings; however if you supplicate Allah for your needs after reading it then it is far better.
(3) Read it in the state of wudhu and taharah, in-shaAllah, you shall have no harm.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.