cells' references (last, first, etc.)? ; cells' modifications ; cells' time format from a number to hours not days?

[Radoslaw Garbacz <rgarbacz aycan de>]

Hello,

This is my first post to this newsgroup, so at first I would like to
thank for the great work done with gnumeric - I find it a very usefull
tool with a very nice user interface.

1) I would like to ask about the possibility to address cells using
keywords such as:"last" (e.g. the last not empty), "first", "current",
etc., e.g. $A$1:$A:$last - is there a way to do it with gnumeric, or
maybe my problem is the academic one and such addressing is not needed.

2) When converting the format of a cell with value e.g. 5 from "general"
to "time" the value is always treated as the number of days - is there a
way to change it?

3) Is there a way to reference the regular expression submatches (e.g.
with "sed" like syntax) to modify cells' values, e.g. to replace
"\([0-9]*\)" with "\1:00"? 
I have found the way to use reqular expressions for search/replace, but
have not found the way to reference the submatches.

I am sorry if my questions are too trivial - but I have not found the
answers so far.

Thanks in advance
-- 
Best regards
.Radoslaw Garbacz
.aycan Digitalsysteme GmbH