Do commandos go commando?
What about other soldiers?
You're asking a paratrooper about the marines and expecting a mockery-free answer? I'll advance naked-roll-mat-jousting and say no more.
Serious note: I've heard of it being done, but I haven't myself and don't know anyone who has.
How hard is it really to get in to the military?
It depends on your branch of choice, but I'd say that anyone who isn't a liability intellectually or physically (there are no qualifications required for a teeth arms soldier, but you don't want to be platoon mong), has determination and a sense of humour will get on well enough. Specifically on the fitness side it varies, but entry is primarily done off the time it takes you to run a mile and a half (a touch under 2 and a half kilometers) - a paratrooper needs 9 minutes 14 seconds, infantry are 10:30 although they sometimes accept up to 12, and this rises to about 15 minutes for 'backroom' jobs such as intelligence and HR. If you've got the determination, however, you can train to this level whoever you are - you don't have to be an athlete although there will be the one annoying little thing who can do his run in 7 minutes while chatting to the PTI.
What is the breakdown of units in military organization?
I mean like Division > Brigade > Squad only with more detail.
What is larger and what is organized into what?
It generally goes in threes:
In order:
The British Army - commanded by Her Majesty the Queen
Theatre (1 or more Army Groups; eg British Forces Europe) - commanded by a Field Marshal
Army Group (multiple armies; eg Army Group North) - commanded by a Field Marshal
Army (multiple corps, eg British Army of the Rhine) - commanded by a General
Corps (about three divisions, eg I (BR) Corps) - commanded by a Lieutenant-General
Division (about three brigades, eg 1 (UK) Armoured Division) - commanded by a Major-General
Brigade (about three battalions, plus supporting assets); eg 16 (Air Assault) Brigade) - commanded by a brigadier
[Regiment (1-4 battalions): ceremonial only; eg The Parachute Regiment]
[Battlegroup (1 battalion with supporting assets); eg Coldstream Guards Battlegroup]
Battalion/Commando (5 companies/squadrons; eg 2 PARA [equivalent to a US Regiment]) - commanded by a Lieutenant-Colonel
Company/Squadron (3 platoons/troops; eg B Coy) - commanded by a Major
Platoon/Troop (3 sections; eg 18 Platoon) - commanded by a Second Lieutenant, Lieutenant or Captain
Section (10 men; eg 2 Section) - commanded by a Corporal
Fire Team (5 men; eg C Fire Team) - commanded by a Lance-Corporal
Is there anything being done to mitigate the damage caused by incoming email?
You mean that incident with the SDSR sackings? I should imagine that the (relatively junior) officer whose fault that was will recieve a severe interview without coffee; however the problem was not a systematic one and so I doubt that any large-scale action will take place