It's the same thing as BSD Jails, however there is one big difference with Docker. A container/jail can be shipped to another system running a completely different kernel. This means you can create an Ubuntu 10.04 container and run it on an Ubuntu 14.04 host or RHEL 7 host.
With BSD Jails, you can only ship your jails to the same system unless you spend enough time fiddling around so you can basically do the same thing. Luckily the Docker team is already adding BSD Jails support.

1, That is not really a problem. If you know shell scripting and SSH you have basically unlimited power. Its not even much work administrating 10000000 computers.

2, I don't know about this, most likely Exchange is more polished. Anyway, I would use a local cloud provider for email. There is no point wasting resources administrating mail myself.

3, Shell scripting and SSH again? Not really a problem at all.

4, Access control list (ACL) ?

5, Do you need encryption if you don't have any read access?

6, I don't understand the problem....

Raspberry Pi +
Raspberry Pi Camera +
dummy camera http://www.ebay.com/itm/NON-FUNCTIONING-SECURITY-CAMERA-/171187177851?pt=US_Dummy_Cameras&hash=item27db8d097b +
Buck converter http://www.ebay.com/itm/LM2596-USB-DC-DC-Step-Down-Adjustable-Power-Supply-Module-LED-Voltmeter-Needle-/360719055201?pt=LH_DefaultDomain_0&hash=item53fc87f961 +
PoE Power Over Ethernet Injector Splitter Adpater Cable http://www.ebay.com/itm/PoE-Power-Over-Ethernet-Injector-Splitter-Adpater-Cable-/390700244783?pt=LH_DefaultDomain_0&hash=item5af78c9f2f

FreeBSD is very well documented (The manual is awesome) and it has a great community. There are a lot of good discussions on the mailing list, and it doesn't require you to be a kernel hacker to participate. I use both Linux and FreeBSD, they both have their strength and weaknesses. I slightly prefer FreeBSD, as I feel its easier to turn it inside out(for hacking).

Btw. Poul-Henning Kamp tweeted this a few days ago.
Between FreeBSD, Varnish and Ngnix, at least 2 out of 3 packets on the net are delivered by #BSD licensed open source software. #EatThatRMS

So I would say, FreeBSD is a lot more interesting today, than 10 years ago.

Stay away from Owncloud....really, those guys don't even know that all modern filesystems have an API for watching changes in your filesystem. And syncing works on file level instead of block level.

In Scandinavia we have to use a java applet called BankID for login to our bank account. This has for the past few months become REALLY frustrating for people who really don't know what Java is. Even technicians who has a basic understanding of what a computer is, has problems keeping Java up to date(they don't know where to download it, and therefore accidentally download something they shouldn't) and all the them are infected with that Oracle search toolbar malware.

Pandas http://pandas.pydata.org/ is another great tool for data analysis. It use numpy and is highly optimized with critical code paths which is written in C.

If you are testing if the person can program or not, then it's fine. But if you're looking for only the cream of super software developers, then something minor as the persons emotional state for the day can make a huge impact on the result.

For me personally, I think understanding the actual question is the most difficult part. Some people find bizarre mathematical puzzles fun. I prefer puzzles from the real world, like for example how to get two systems to talk together.

There are many reasons!

Jails
ZFS
GEOM Framework
Ports
PF
Carp
Hast
The FreeBSD Handbook / Documentation with consistency

However FreeBSD doesn't excell for everything, for example Java support is far away from production ready. And another thing I ran into recently was that monitoring a lot of files for changes was slow/not scalable at all because kqueue uses file descriptors for monitoring changes in your filesystem. Linux, OS X or even Windows have scalable and working solutions for this.

Not only have you created an amazing tool, it is open source and the best part...it's actually well documented! Christmas came early this year!

Hammer can do deduplication with minimal memory requirements. For example only 512MB ram would still give a responsive and fast system. Hammer deduplication doesn't take a hard hit on performance like ZFS does, as ZFS dedup data in realtime while Hammer does it with a CRON job.

I'm not using BTRFS yet, however as send & receive in BTRFS is similar to the ZFS send & receive implementation you can do really cool things like superquick backup of a gigantic PostgreSQL Database.

The workflow is as following
Execute "pg_start_backup(‘snapshotting’,true)"
Snapshot the filesystem with PostgreSQL data
Execute "pg_stop_backup()"
Send the snapshot to your backup server

So if I run PostgreSQL on Windows I can be sure VSS executes psql -c "select pg_start_backup(‘hourly’,true);" before creating the snapshot?

My FreeBSD PostgreSQL backup looks like this and runs hourly.

#!/bin/sh
prev=`date -v-1H '+%Y-%m-%d_%H'`
now=`date '+%Y-%m-%d_%H'`
psql -c "select pg_start_backup(‘hourly’,true);"
zfs snapshot tank/pgsql@$now
psql -c "select pg_stop_backup();"
zfs send -R -i tank/pgsql@$prev tank/pgsql@$now | ssh backup@hpbackup zfs receive -Fdu tank/backup/pgsql

You can do the similar thing with Linux as BTRFS now support send and receive.

You forgot step 7 for Windows. Click ok for administration mode and next, next, next, and finally make sure to hook off those extraordinary browser bars.

Been there myself. There are so many good looking nuts out there, a dangerous world for a peaceful man.