2005 Jeep Grand Cherokee 5.7 HEMI Questions

Hopefully an expert will be able to answer a few of my questions.
1) I have observed 5th Gear overdrive does not kick in until >65mph.
Generally I cruise (Where legal) at around 60mph and this means 4th
Gear at around 2000 rpm. My previous 4.7 HO Overland, used it's 5th
Gear Overdrive from around 50mph.
Do I need to speed up? Or can it be adjusted?
Or is 4th Gear at 2000 rpm at 60mph as efficient as 65mph at 1600 rpm
in 5th Gear?
I feel uncomfortable driving fast in this thing, it's so big especially
on A roads.
(And before anyone says, why by a HEMI 5.7 if you're worried about fuel
economy! I'm not, just interested in it's use of the gears!)

2) MDS. Is it possible for this to be disabled? Driving at 65mph I
can't seem to get any more than mhy old 4.7 (Which didn't have MDS). I
know this is a 5.7, but with 4 cylinders wouldn't it be better?
Official highway/urban/combined economy all showed it was?
(Yes ok I am a little concerned about economy, but only since I was
sold MDS as better economy than my older 4.7 HO)

3) Hands-free. The HEMI comes with a superb navigation unit. MP3,
6-Disc changer and hands-free capability. However the UConnect
hands-free option is not available in the UK. Dealers say it's
withdrawn and not available.
Would a US UConnect work in our UK REJ system?
Why the withdrawal, I can muster an American accent if required.
"I know what you're thinking. Did he fire six shots or only five? Well,
to tell you the truth, in all this excitement, I've kinda lost track
myself. But being as this is a .44 Magnum, the most powerful handgun in
the world, and would blow your head clean off, you've got to ask
yourself one question: 'Do I feel lucky?' Well, do ya punk?"

4) DVD Playback on the REJ navigation unit.
Says 'error reading disk'. My research suggests it's not possible to
play movies with the installed REJ Navigation system.
However there is an aftermarket upgrade from G-NET (Canada)
http://www.gnetcanada.com/navvideo-models-gnetrgbd.htm
Unfortunately it requires the entire unit to be sent away for the
upgrade.
Are there alternatives for other video inputs or a fix to play DVD's?

5) Passenger front seat, no height adjustment. Is it possible to have
the seat updated. My girlfriend finds it's difficult to see over the
larger dashboard and would airbag be still be effective?
May consider taller girlfriend :-)

6) SmartBeam. Available in the US as an option.
http://www.wkjeeps.com/wk_smartbeam.htm
Is it legal and possible to have installed in the UK?

That'll do for starter! Thanks in advance. Allister