All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
You should be encouraged to befriend other Muslims, involve yourself in Islamic activities, and not to live alone if you can find a pious Muslimah to share living with you. We ask Allaah to remove these whispers from you and repel the plots of the devil from you.
We answer your question in the following points:
1) Ruqyah is protecting oneself with the Quran and legislated mention of Allaah and supplications, these are read to the patient to be a means for his cure. A Muslim can read any verse from Quran for this purpose. Allaah says (which means): {And We send down from the Qur'an that which is a healing and a mercy to those who believe (in Islamic Monotheism and act on it.}[Quran 17:82]. Imaam Maalik reported that Abu Bakr entered upon 'Aa'ishah and found a Jewish woman making Ruqyah to her, then he told her: "Make Ruqyah to her with the Book of Allaah." However, one can read some special chapters or verses of the Quran, like Al-Faatihah (the opening chapter), verse 2:255 and chapters 112, 113 and 114. For more details, please refer to Fatwa: 82917.
2) These whispers are among the plots of the devil to spoil the person's religion and make his life miserable. So we advise you to ignore these whispers and repel these bad thoughts especially those that are related to belief, and seek refuge in Allaah from them. Refer to Fatwa: 86235.
3) One of the rules in Islamic jurisprudence is that firm belief is not removed by doubt. So if you have ablution and are sure of it, then do not take into consideration any doubt after having ablution. Doubting after performing an act does not affect its validity. Even if you doubt too much, do not consider it even when performing an act of worship.
4) The Prophet is the best Prophet and the most pious person ever, and he supplicated Allaah saying: "Oh Allaah! Do not turn my grave into a worshipped idol." [Maalik] So it is not permissible for any person to believe that a grave can benefit or harm, as it is only Allaah Who can benefit and harm. Hence, it is forbidden to circulate around graves or ask the person who is buried in it for any kind of help or assistance, or other things that the ignorant Muslims are doing. This is indeed a falsehood that one has to condemn. On the contrary, graves are visited to remember the Hereafter and supplicate Allaah to forgive them and have mercy on them. If one believes that a dead person in his grave can harm the person who denies such acts [seeking help and the like from them], then this is like those who told their Prophet as Allaah says (which means): {We only say that some of our gods have possessed you with evil [i.e. insanity].}[Quran 11:54].
Allaah knows best.