Surely a Deadpool movie is going to have to be funny Deadpool. In the limited time he was on screen (and in plently of other movies and TV shows) Ryan Reynolds proves he can do the never shuts up always cracking joke routine.
As far as I recall, Wolverine's time in Japan happened after he joined the X-Men, and he was never a 'Samurai', he just you know fought with honour and stereotypical stuff like that, loved the daughter of a crimelord, adopted an orphaned girl, fought ninjas etc. But I could be wrong. Wolverine's past is half false memories and confusion anyway, and I think the end of credits scene was setting up the next movie to feature Mariko (and Silver Samurai would make a cool villain for it).