Answering your cycling questions

More water resistant than water proof. The casing closes quite tightly and is likely to resist most rain. You won't be able to submerse them in water though.

I would not immers them in water, but they are enough waterproof to use on a raining day despite they do not have any ruber to protect the inside from water.

It is very high water resistant.

It depends what you mean by waterproof. They are fine in the rain, but i wouldn't take them swimming.

rain and splash proof, rode in snow and rain without any problems.

I've been out in the rain and they seem fine. the front light doesn't seem as well protected (with rubber seals etc) as back, but I'm guessing it's fine - it not I'll return it.

I'm not sure if they are certified as waterproof but I did a few miles last night in torrential downpour with no operating issues. The front unit particularly fits together really tightly and I do believe they have a small seal to try and keep water out. Don't take em in the bath but short of that I feel they'll put up with the worst that winter can throw at them!

The speedo I think is waterproof and the back light looks reasonably waterproof but the front light isn't as when you open it there are no seals inside.

The lights can be easily removed, so you can take them with you. Therefore I'd have to say no. If you leave them on your bike then yes.

if you leave them on your bike - yeah, sure.
if you remove them, no! The removal is really simple and quick and the lights are small enough to fit inside a pocket

not if you remember to take them off when leaving the cycle. otherwise like most others, yes.

These lights are easily clipped off the bike when not in use. They are compact, so don't take up too much space to store away in a bag or pocket.

Most lights including these ones can be easily taken off, they have a bracket which fastens to the frame then the light clips on. Theerefore any would be easy to steel if you left them on it when you've parked it up.

I would always recommend taking the lights (and anything else which can be easily removed such as cycle computer, bottle etc) off when you lock up a bike securly using a d-lock. .

mmmmmm, if you leave lights on a bike they will get nicked. Take them off!

There is nothing on the packaging to indicate that this set is BS Certified so I would assume that it is not to be safe.

You can use this on its own in the flashing mode. On constant you will need a BS light as well.

No

Ive checked the box and it says "for the UK market these lights should be used in conjuction with cyle lights to BS6102/3"

That's 11cm, so yes, they will.

there is a lot of excess strap length which you can trim to suit your own bike. I have regular sized handlebars and have around 2.5 inches of excess strap available

I have the EL210 front light and just tried it around a piece of wood with a diameter of slightly over 3.5cm - it just fits, and is secure. Any bigger and it will not fit.
As long as the fitting strap is the same - which it appears to be, then you should be fine.

I'm sure that it would, but it would be more sturdy if fixed to the handlebar.
Maybe it'd even fix to the front fork?