Win 2008 R2 showing Pagefile drive almost 100% full : any concern?

Refer to attached screen.

IBM field engineers installed Windows 2008 R2 (Standard & Enterprise)
on our x3650 and x3850 : they allocate almost 100% of the space to
Y: drive.

Q1:
Is this a cause for concern that the drive is almost 100% used ?

Q2:
What's the usual practice?  To allocate only 80% of the drive for
pagefile?  

Q3:
By allocating almost 100%, will it affect Windows/systems' performance?

Q4:
Will this pagefile grow or it will stay at this 99.x % all the time?

Q5:
Windows will occasionally flash out a brief message (which I was not able
to capture as it's too brief/momentary) saying Y: drive is almost full. How
to disable this message (so that others don't get alarmed unnecessarily?).
Would setting it in the registry below disable this message :
  HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
  NoLowDiskSpaceChecks   REG_DWORD  1

Q6:
Does anyone set Tivoli to monitor the Y: drive utilization (or the drive
that houses the pagefile) ?
PagefileDrvFull.jpg