Some problems with times in a spreadsheet

[Cecil Westerhof <cldwesterhof@gmail.com>]

I have the following table:
|---+-------------+------------+------------|
|   |         Day | ProjectA   | ProjectB   |
|---+-------------+------------+------------|
|   |          14 | 1@ 00'     | 1@ 45'     |
|   |          15 | 0@ 30'     | 3@ 35'     |
|   |          16 | 0@ 45'     | 1@ 00'     |
|   |          17 | 3@ 10'     | 2@ 45'     |
|   |          18 | 1@ 55'     | 0@ 35'     |
|   |          19 | 5@ 25'     | 7@ 25'     |
|   |          20 | 3@ 30'     | 1@ 00'     |
|---+-------------+------------+------------|
| # | Total hours | 16@ 15' 0" | 18@ 5' 0"  |
| ^ |             | totalTime1 | totalTime2 |
|---+-------------+------------+------------|
#+TBLFM: $totalTime1=vsum(@-II..@-I); f2 :: $totalTime2=vsum(@-II..@-I); f2

The string '0 @ 30' says that there were 0 hours and 30 minutes.

I have several problems here.

First of all I would like to see 16.25 instead of 16@ 15' 0". Is this
possible?

Secondly I have to define the formula for each project. In this case
there are only two, but when there are fifteen then it becomes a pain.
Is there a way to use just one formula?

When displaying with minutes instead of as a floating point number, is
it possible to display it without seconds? Instead of 16@ 15' 0" I would
like to get 16@ 15'.

-- 
Cecil Westerhof
Senior Software Engineer
LinkedIn: http://www.linkedin.com/in/cecilwesterhof