I used Arch for four years before switching to FreeBSD as my main OS about three weeks ago. The similarities are almost uncanny, so the switch was pretty easy. Arch is great and FreeBSD shares a lot of its characteristics, but improves upon most of them. That last point is going to be the gist of my answers. I've kept my Arch install to tinker with too, so as someone who's very familiar with Arch, new to FreeBSD and currently using both, here are the answers to your questions I've gleaned from the experience:
a) is there a live version so I can see what it's like before installing?
Yup, in the same way there's an Arch LiveCD. It's just a live environment you can boot into via the installation image. As with Arch, playing around with a graphical LiveCD with a bunch of pre-installed stuff won't tell you anything about the OS itself, as all that graphical stuff isn't really part of the operating system. It's just extra stuff installed on top of the operating system. The separation between the base system and the extra user-installed software is much greater than the separation between Arch's [core] repository and its other repos.
b) can I make dualboot FreeBSD<>Arch?
You can boot FreeBSD with GRUB. The FreeBSD boot menu is supposed to also detect multiple operating systems installed on the same disk, though I've never seen that since I use one OS per disk.
c) is the directory structure much different from the Linux one (home, docs etc)?
It's very similar better. Both GNU/Linux and *BSD have a
hier(7) man page; the difference is that FreeBSD (and the other BSDs, I presume) actually stick very closely to the defined structure, while the Linux FSH varies between distributions, isn't strictly kept to and the man page is out-of-date. Under FreeBSD every major directory serves a specific purpose, which makes it easy to make educated guesses about where various files are stored when you need to find them. You can still use tools like [command]find[/command] and [command]locate[/command] if you wish.
d) is FreeBSD using kernels from Linux or custom (specially designed) ones?
FreeBSD has its own kernel. There are two differences to be aware of. First, configuring a custom kernel in FreeBSD is insanely easy. I still have a lot of love for Linux, but the tedium of configuring and building a custom kernel in Arch relative to the ease and speed of doing it under FreeBSD cannot be overlooked. The second thing to note is that FreeBSD is a complete operating system---all of its components are developed and maintained together, including the kernel, so the kernel source is synched to the rest of the operating system source.
e) is it meta or binary OS?
Either. In a general sense, software management under FreeBSD and Arch Linux are virtually identical. You can either install built binary packages with the
pkg package manager, or build your own custom packages from the ports tree. The main difference is that unlike the Arch Build System, the ports tree is designed so that all your user software can be installed and updated from source, so it features dependency resolution and interactive customization. But you can mix the two all you like---all ports, all packages, or mostly packages with just a few custom ports, for example.
f) how 'rich' are its repo(s)?
There isn't nearly as much software available in the FreeBSD ports tree as there is in the Arch repos and AUR, but just as you can write your own PKGBUILDs you can write your own
Makefiles. If you're using a minimal setup in Arch there's a really good chance most of the software you use is available in the FreeBSD repositories/ports tree. I run a really minimal system, so I'm lucky enough to have Arch and FreeBSD systems that are identical on the surface.
g) how often does it get updates?
That's a more complex question than you might think. FreeBSD has a similar development cycle to Debian, with -RELEASE (Stable) -STABLE (Testing) and -CURRENT (Unstable) branches. The -CURRENT branch is just the HEAD of the SVN repository that's used for FreeBSD development, and can function as a Gentoo-style rolling release if you want, while -RELEASE branch only sees an update a couple times a year, with the exception of security patches. -STABLE is a sort of mid-point between those two extremes. The ports tree and package repositories get updated fairly often, though the update frequency depends on which of the three branches you choose to follow.
h) does it support UEFI/standard BIOS?
I'm booting UEFI on my Thinkpad without any trouble. Every OS ever supports BIOS.
i) is it possible that FreeBSD reads and 'adopts' Arch /home partition (I mean will all the docs be editable, scripts runnable etc) or do I have to make separate /home just for FreeBSD?
You can use your existing /home partition
if it's formatted in EXT2 or EXT3, but I wouldn't recommend it. Native filesystems are preferable, and the
/home directory on FreeBSD exists under
/usr/home. The separation of system data and user data means partitioning is a little different. Under Arch I used an 8g
/ partition and gave the rest of the disk to
/home. On my FreeBSD system I give 4g to the base system and the rest of the disk to
/usr.
