Despegue
Personally, I think that I have good radio etiquette.
However:
1)can I aknowledge "GSM123 Climb FL350, level abeam Lakey" by saying:" Climb FL 350 WILCO"?
I would say that you have to read the clearance back in full.... if you just reply "GSM123 Climb FL350 WILCO", the wilco (will comply) could be inferred as meaning that you will comply with the climb to FL350 and not the "Level By" restriction.
The vagaries of English I'm afraid, you could be construed as reading back the "climb FL350" part of the message as almost repetition for confirmation and/or checking and not as acknowledgement that you will actually do it - all because you added the "wilco".
"Wilco" is an old piece of phraseology, although perfectly valid, but it is supposed to be used for more routine conversation and not for mandatory readbacks.
For example if your wife was an ATCO and happened to be controlling you as you were making an approach (ooh err missus) and she passed the message "Feed the dog when you get home", you could just reply "Wilco".
(Or you could tell her to do it herself as you were off to the pub).
By the way, I am not advocating discussing domestic arrangements over the R/T!!
