Answering your cycling questions

yes really easy, even with gloves on!

Yes, the light can be removed very quickly from it's handlebar bracket by pressing a small catch at the front of the bracket, just underneath the light. The handlebar bracket can be removed from the bike fairly quickly by unscrewing the thumbwheel, but the instructions say that the bracket is intended to stay with the bike and that the thumbwheel can be replaced with a standard M5 bolt, allen bolt or torx bolt if a little added security is required. Spare brackets are available from Evans Cycles or direct from Lezyne.

Very easy - not a problem. Also seems secure when on bike.

Yes very easy. Push the clip down and slide the light forward. 2 second job, can even be done with one hand.

Yup, it can be removed very easily.

I take this on and off in under 5secs.

Yes. Takes a second.

very easy to set bracket up and one simple push of release and light slides out with no problems can be done with gloves on or off !

Absolutely. Mounting and dismounting takes less than five seconds without breaking a sweat.

The tab below the 'E' on 'LEZYNE' is pushed back towards the bracket and the light slides forwards off the bracket.

The battery is very easy to replace, you just unscrew the cap at the back of the light. The battery is a standard 18650 rechargeable battery which can be bought from retailers such as Maplins. The Superdrive will run at full power for 90 minutes per battery.
There is currently (January 2012) no helmet mount for the Superdrive, but Lezyne will be releasing one later this year after constant requests for the accessory from mountain bike riders.

Just unscrew back of light and battery can easily be replaced. Make sure spare is charged, No specific helmet mount with product as delivered, Could search Leyne website?

Simple. Battery changing works as if it were an ordinary battery. No helmet mount with the product

The battery is easily accessible through the rear of the light - simply screw the back off. However, the Li-ion battery that comes with the light should last a good few years if it is looked after and with it having no memory and being USB chargeable you will be able to charge it at the office to make sure you have enough light to see you home.

Yes - but you'll need to buy Lezyne helmet mount

Not at the moment (January 2012), but Lezyne are going to release one this year as they have had so many requests for this accessory from mountain bike riders. The prototype mount they had at a recent bike show was basically the top bracket from the handlebar mount with a velcro strap attached.

The Superdrive does not have a separate battery pack, it runs on a single standard sized rechargeable 18650 battery. The light comes supplied with a good quality Lezyne branded battery, but replacements are available from many retailers such as Maplins. You access the battery by unscrewing the cap at the back of the light.
The Superdrive will run at full power for 90 minutes on one 18650 battery, but obviously the light's party piece is that if you need more run time, you can simply take additional batteries on your ride.
At 450 lumens the Superdrive is firmly in the 'light up the road in front of you' category of bike lights and has a very bright, wide beam pattern. Highly recommended.

No extra battery pack needed - it is neat compact and has good quality bracket. When off bike just charge via usb to computer and good light for 60 mins (not used longer than this without charge - info says should last longer