I have 2 standard objects and 1 custom objects.I want to fetch some specific fields from each of these objects and display in one visualforce page.I am quite new to vf pages.Can you provide me with sample code in order to achieve this requirement?

I have an application(custom object).I want to create a custom button named "submit" on application which when clicked change the record type of application.Please help

There is an picklist field named status on account(std object) which is intially set to draft(default).Account and opportunity are linked by std lookup field.I want to ensure that only when the account status change to complete then only an oppotunity can be added to account from account related list.How to achieve this requirement?

There is an picklist field named status on account(std object) which is intially set to draft(default).Account and opportunity are linked by std lookup field.I want to ensure that only when the account status change to complete then only an oppotunity can be added to account from account related list.How to achieve this requirement?