Is it safe to do banking with the iPad

There are no known viruses in the wild for iOS. A virus isn't what you should be concerned about with on-line financial transactions, general security is. The iPad is as safe for banking as any other electronic device (safer than many, in fact). But use a little common sense about where you do this activity and protect your login information.

Best bet would be if your financial institutions have apps rather than using a browser. Check the app store or your institutions website/customer service.

There is no built-in anti-virus, but then again I'm not aware of any iOS viruses. As long as you are on a secure network (e.g. I wouldn't do banking on a coffee shops network) then you should be ok - a number of banks also have their own apps in the app store.