Is it wrong to encourage conversions to Islam by giving monetary or materialistic benefits as  a symbol of support , help and brotherhood ?  

Also, There is a verse in the Quran that defines people who are eligible to receive charity money (Zakat). Among them are people who newly embrace Islam so is this encouraged?

Are there any examples from the Prophet's pbuh  history wherein  he gave gifts or other benefits etc to encourage conversion to Islam?  Can his other 10 marriages be seen as an attempt to reconcile\unite  and encourage the warring non Muslim tribes to embrace Islam?