1. Recordings with land revenue department dos not indicate ownership of the property, registered Title Deed does. bank can not mortgage a jointly owned property without taking signature on the mortgage letter by both the owners. Here your mother's share was shown as sold to X for which Bank has taken signature of X only ,
2. Bank can disburse amount based on sale agreement also but in that case there will be no mortgage of property and the said loan will be unsecured,
3. Bank will not and need not check the revenue records. It is required to search about the title holder from the Registry Office,
4. It was not possible earlier. but now a days the buyers can chvk through CERSAI site. CERSAI i,e, Central Registry of Securitisation Asset Reconstruction and Security Interest of India is a company wherein all Banks register details of all the properties which are mortgaged with them,
5. No. Be it rural or urban, title of the properties are not established by mutating names in revenue records.Only recording names as before he Registrar by paying stamp duties and registration fees buyers establish such ownership. In the instant case the sale deed of your mother in favour of X has been forged. So, the matter ends there. Bank should hve made registry check before mortgaging the property. It is a bad mortgage. keep an eye on the Demand and posession notice which will be served upon X and pasted on the property under SARFAESI Act,2002. On receipt of the Possession notice u/s13(4) of the Act, your mother shall have to file an application u/s17 of the Act before the local DRT challenging the mortgage.