I would like to ask the difference between the Sunnis, Wahabees and Salafis. Please also tell me what is the meaning of Muhammadans - the follower of Prophet. Also what is the difference between them and who is likely to be the best slaves of Allaah?
Also I would like to ask you that I am a Muhammadan and I pray only to Allaah but also while praying I ask the Prophet - Rasull Al Rabb Al Alamin to pray for me. Is this a Shirk or will Allaah get angry if we do so? Please reply. I am just praying to Prophet so that he might pray for me but I don't think so I am so worthy of it.
Please advise me as soon as possible because this is very important.May Allaah keep all His and the followers of Prophet away from Shaitan and Kafirs.

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.

We have already issued Fataawa 85146, 81463 and 86236 on Wahabism and Salafiyyah, so please refer to them.

As regards Muhamadans, we do not know any group that is named by this name. However, some researchers mentioned that the group that is affiliated to Shaykh Abdalwahaab said that it is named with this name previously. Nonetheless, it should be noted that following the guidance of the Prophet is the best objective which every Muslim aims to achieve, as it is a means of achieving guidance and obtaining the love of Allaah, and the success in this life and in the Hereafter. Allaah Says (what means): {…and follow him [Muhammad ] that you may be guided.}[Quran 7158]. Allaah further Says (what means): {Say, [O Muhammad, sallallaahu ‘alayhi wa sallam], ''If you really love Allaah, then follow me, [so] Allaah will love you and forgive you your sins. And Allaah is Oft-Forgiving and Most-Merciful.'}[Quran 3:31]. In another verse Allaah Says (what means): {So they who have believed in him, honoured him, supported him and followed the light which was sent down with him — it is those who will be the successful.}[Quran 7:157]. As regards asking the Prophet to supplicate on your behalf, then we do not consider this as an act of Kufr [an act that takes a person out of the fold of Islam] but it is a matter that is not reported that the scholars and the pious people from our Salaf did and we do not know any evidence that it is legislated.

However, since supplicating is an act of worship, then it is an obligation to abide by the Islamic Law in its regard, and stay away from innovations as the Prophet said: "Whoever performs an act that is not in accordance with ours (concerning religion), it will be rejected." [Muslim] 

Allaah Knows best.