Is there any info somewhere on the limits of meta unit?
Yes look around the Forum, I am sure you will find the Dev's Talking about it, sorry cannot give you a link right now, just do a search.
And can i somewhere see current logistics use on my meta unit (or free logistics to add to meta unit) or do i have to count it myself?
I think you need to count them by yourself right now.
Can i group two or more meta units in a single group via ctrl+1?
you can have as many Meta-Units as you want inside a Ctrl+#, they just don't work together.
So i did some testing. As you mentioned it all went fine when i didnt make large meta units. But game really needs some clarifications on meta unit limits.
Yes it does, they need to add some kind of Tutorial for that to explain about it and the reason of why they have a Cap for each Meta-Unit, but i think if I am correct the main reason to cap each Meta-Unit is because of the buff that they get together.
Really big buffs, and that does not make me very happy, I think the Dev's need to double or triple that Cap and lower the Buffs.