1. Instead of defaulting to date/time, default something that looks like a date to date. A lot of times, text files has a useless timestamp portion of an incoming field (00:00:00) that can be ignored.
2. Unless an incoming column has 'dollar' or 'amount' or 'amt' in the name, default it to string. There are so many 'codes' and 'numbers' like zip code, social security number, employee ID and so on that just have numbers in them but nobody ever performs numeric functions on them, so import them as strings (especially important for leading zeroes).
These could be 'check boxes' on the import wizard screen or options for EG.