Hi Mr. Wilde,
SharePoint stores data in SQL. Those are SQL data type conversions. Your InfoPath form's data source can have fields that are of type date, time, or date and time. So, just change it to Date only and you should be good for the first one. For the second, it's a bit more complicated since double is converted into a decimal. InfoPath has mantissa issues. I recommend storing it as a string and having another field with a default value that has a fx of number(field1) where field1 is the string field with the string number.
Some random thoughts for ya.
How's the emu?