Yes, it can be used for older iMac as well (i.e. with Thunderbolt 2 ports) and all ports will work.
However, you must use a USB-C (f) to USB-A (m) adapter to attach the USB-C cable to a USB 3.0 port of your iMac.

If the symbols “°/^” (symbol beneath “esc” key) and “</>” are reversed, you can swap them by pressing “fn + °/^” (“fn + [key below “esc” key]“.

In some cases, attaching the Compact Dock with the power cable (Power Delivery) plugged in can lead to a non-recognition of the attached peripherals.
Follow these steps:

• Disconnect the Compact Dock from the host.
• Disconnect the USB-C power cable (Power Delivery) from the Compact Dock (while other connections to peripherals can remain attached).
• Attach the Compact Dock to the host.
• After the Compact Dock has been plugged in, you may plug in the USB-C power cable (Power Delivery).

In order to use the Mini-DP port as an HDMI output and connect 2x HDMI monitors or TVs, you must use an active Mini-DP to HDMI adapter or cable (must be “active”!).

No. The Compact Dock has 2 USB-C connectors that must be plugged in and therefore can’t be used with the 12″ MacBook which only has a single USB-C port.

It is normal that any USB-C hub or dock becomes hot when attached to the laptop. The aluminum housing is meant to dissipate the heat from the inside to the environment. There is a number of chipsets working on the inside which are producing some heat since they are constantly in a stand-by position to react quickly should any port be used. The surface temperature is well within the allowed limits and reaches about 40° C in stand-by mode, 43° C under normal use and a max. of 48° C when all ports are in full use, CPU load at 100% and PD attached. The heat does neither pose a danger to the laptop or any attached device, nor does it influence the USB-C hub’s/dock’s performance or even shorten the life-span.
Furthermore, the surface appears to be hotter than it actually is since it is touched with the very senstive fingertips. We suggest to remove the USB-C hub/dock when not needed in order not to emitt unnecessary heat to the environment and not to use any energy.

There is already a set of rubber pads attached to the Compact Dock so it fits perfectly the 13″ MacBook Pro. The additional pads can be attached on top of these for fitting it well with the 15″ MacBook Pro. The rubber pads prevent unnecessary strain on the USB-C ports of the laptop by bridging the gap between Compact Dock and desktop.

By pressing “fn + esc” keys, the top row of keyboard is changing from system functions (such as “brightness up/down” or “volume up/down”) to true functional keys (F1, F2, etc.). “fn + esc” changes back and forth between system functions and true Fx keys.