[O] agenda time grid -- default time slot lines

[hymie!]

Greetings.  I have two questions about the default time slots in the Agenda.

First question

When I open the Agenda Day View, I get a bunch of blank lines at the
default times 8am, 10am, 12noon, 2pm, 4pm, and so on.

Friday      3 October 2014
               8:00...... ----------------
               8:50...... now - - - - - - - - - - - - - - - - - - - - - - - - -
              10:00...... ----------------
              12:00...... ----------------
              14:00...... ----------------
              16:00...... ----------------
              18:00...... ----------------
              20:00...... ----------------

Then I did a few tasks, so my agenda for today looks like this:

Friday      3 October 2014
               8:00...... ----------------
      tasks:   8:45- 9:10 Clocked:   (0:25) first attempt failed
      tasks:   9:10- 9:45 Clocked:   (0:35) troubleshoot
      tasks:   9:45-10:45 Clocked:   (1:00) restore image
              10:00...... ----------------
      tasks:  10:45-11:25 Clocked:   (0:40) second attempt
              12:00...... ----------------
              13:20...... now - - - - - - - - - - - - - - - - - - - - - - - - -
              14:00...... ----------------

Is there a way that I can suppress the 10:00 line in this case?

None of the org-agenda- variables that I found seemed to do this.

Second question

My Agenda for a-week-from-next-Tuesday looks like this:

Tuesday    14 October 2014
               8:00...... ----------------
              10:00...... ----------------
              12:00...... ----------------
      tasks:  14:00-15:00 IT-Security meeting
              14:00...... ----------------
              16:00...... ----------------

Assuming that I cannot suppress the 14:00 line in this case ...
shouldn't the task line be **below** the 14:00 line?  I can "force"
it by changing the meeting time from 14:00 to 14:01, but it seems like
this is the wrong way to list them.  The meeting is not between 12:00
and 14:00.  It's between 14:00 and 16:00.

Thanks.

--EbH