Problem with time fields in QUERY

[ouuch@xxxxxxxxxxx]

Hello,

I'm doing some time calculations in Query, but I have some problems.

The file has start/end times in alpha format '14:05:30'. I can convert this to 
a time field with
the statement time(starttime).
But when I subtract two time fields as in starttime -endtime the result is 6,0 
numeric?

One of the alpha time fields doesn't have a leading zero when hour is less than 
10 :'
4:58:30'.
The time function doesn't work with a leading blank. How do I solve this?

And finally, what is the best time field format for downloads to Excel (when 
Query produces
a file): 6,0 numeric, alpha ('14:05:30') or time data type?

Thanks,

Oliver