However. Anything I should know about wild barrels?
I believe the wild barrels behave the same as DK, but maybe more experienced Crazy Kongers could weigh in here.
In the version I have (ckong set 1) it's not possible to go through Kong on the rivet lvl although I've seen otherwise somewhere. Is this version connected in som way?
You are correct. In the "legitimate" version of Crazy Kong, its direct clones and Brazilian Kong, you CANNOT walk behind Kong on the rivet level. However, on the other Crazy Kong bootlegs, it is possible.
So, you can't walk behind Kong in the following versions:
Crazy Kong Part II (set 1) - ckongpt2 (MAME 139+)
Crazy Kong Part II (set 2) - ckongpt2a
Crazy Kong Part II (alternative levels) - ckongpt2b
Crazy Kong Part II (Japan) - ckongpt2j
Crazy Kong Part II (Jeutel) - ckongpt2jeu
Kong (Brazil) - kong
You CAN walk behind Kong in these versions:
Crazy Kong - ckong (MAME 139+)
Crazy Kong (Alca) - ckongalc
Crazy Kong (Galaxian) - ckongg
Crazy Kong (Galaxian, encrypted set 1) - ckonggx
Crazy Kong (Moon Cresta) - ckongmc
Crazy Kong (Orca) - ckongo
Crazy Kong (Scramble) - ckongs
Big Kong - bigkong
Donkey King - dking
Monkey Donkey - monkeyd