Use the import then recall the generated datastep code, use F4 or go to the log and copy back into the editor. The variable informat and informat assignments will show in the code. Change them from probably best3.2 or similar to $20. or what ever length you need. Then add a $ after the variable in the INPUT statement corresponding those variables.
You can suppress the warning messages for the dates by using ?? after the variable name in the input statement.
If you are going to read the same data format multiple times generating datastep code this way is very beneficial as you can make adjustments to character variables that may change size such as city names or customer comments and allow additional room for later versions.
Also adding meaningful labels will likely be helpful in the long run.