How do you know, when you move the lever, that it actually does something with the throttle plate?Quote
You don’t, until you start the engine. At which point, if the throttle plate is set somewhere other than where you have commanded, you’re going to find out very quickly – ask me how I know.
Some older carbs have the throttle bellcrank attached to the throttle arm by friction, rather than the positive lock of a pinned, splined joint. With these, if the friction joint has slipped, you’re going to feel a much shorter throttle stroke than normal. Either this will signal the attentive pilot to not start the engine, or, moving the throttle control through the full range will reposition the throttle plate correctly, and things will be fine. Landing with some carb ice, can cause the throttle plate to bind on the ice, and as you close the throttle control, the plate does not close. Ice melts out, and if you do not check the throttle, you’re starting with lots of power set – I’d estimate 1800 RPM for my startling experience with this.
It’s just way easier to check the proper full motion of the throttle before you start the engine, hence my original remark….
And back to the opening subject: on said Rotax 912 there is no discussion, all documents agree that oil temp must be at least 50 degrees C before taking off.
Before starting, I always rotate the prop a few turns by hand, to pump a bit of oil around.
No need to turn the prop by hand. I used to get the oil round the engine prior to start on my Rotax 912 by just leaving the mags off and turning the starter motor for a few seconds. 
As has been said it really is a matter of “know your systems”. There must be as many “best ways” are there are engines and installations.
I understand that with some 912 installations some hand turning is recommended as due to the position of the oil tank it is possible for air to enter the system and in this case the POH has a very definite recommendation that the engine be hand turned to clear the system. This is not the case with many other 912 powered aircraft.
Jabiru engines being mostly aircooled, after start up revs are best kept below 1500 until thoroughly warmed up, this is indicated by the oil temps not the CHT gauge as the heads are the first thing to heat up. There is an oil cooler in the system that greatly restricts flow until the oil reaches a better working temperature, in the summer not much of a problem, the winter though is another matter.
With the Porsche aero engine, you have to start it, warm it up, turn it off, get out, check the oil level and then get back and take off. I always found that to be very annoying. The Porsche like the Rotax has forced-feed lubrication, i.e. no sump.
Technically, that’s called a “dry sump”, and the difference being that the camshaft(s) lobes & followers are directly lubricated versus wet sump that relies on oil being splashed on to the camshaft and followers.
This is important to note and the reason one should run the engine @ 1200 – 1500 RPM when warming it up to ensure that the oil is slung up on the camshaft.
