Probably that darned Pol again.
How would you make this into a question (Isn't he welcome?) - An níl fáilte roimhe?
The negative interrogative particle is nach. Nach bhfuil fáilte roimhe?
Just asking, can you still write "níl" as "ní fhuil" as that's where it came from?
No, you can't. I haven't even seen older natives do that. I have seen ní'l, but that's rare
The courtesy of your hall is somewhat lessened of late.