[Orgmode] Some questions about column view and org mode

[Friedericksen Hope]

Dear all,

I start to like column view. :)

But as I played around with it, a few questions came up:
- Is there some built-in timestamp property? The background is that I would like to have a column with a timestamp in it which I can set manually (but of course, I would like to have the calendar 
opened up when I press "e" on a field of this column, like on a SCHEDULED or DEADLINE column) I found the TIMESTAMP and TIMESTAMP_IA property in the manual, but I was not able to use this for my 
purpose and I also do not quite understand for what they are useful, but this is another topic. ;-)
- If there is such a thing as a timestamp column, is there a summary method 
which gives me the timestamp farest away or calculates the maximum difference 
from today to a timestamp in the past?
- Is there a way to get column view work with repeated timestamps? (I would 
like to have a birthday column with a DEADLINE property and of course, the 
birthday repeats every year.)

And two questions, not specifically related to column view:
- What is the fastest/easiest way to reload an org buffer, so that global settings get loaded (for example changes in global column definitions)? At the moment I close the buffer with C-k RET and open 
it again with C-f M-p RET but this seems a unnecessarily complicated

Thank you in advance for any suggestions/comments and also thank you, Carsten, 
for this wonderful tool. :-)

Greetings,
Friedericksen