Higher trading volume in itself means that the instrument is traded more often. If you’re referring to max position sizes, though - if volumes improve, we can revisit them.
Orders are always filled as per our execution policy. Delays occur as a result of a lack of quotation in the instrument. And as far ar as displaying the spread goes, it is not currently possible because of the LTP - more info 
here.
Interesting idea, for sure, however, I don’t think it’s applicable in practice because " the next possible trade time" mostly depends on when the next available quote would be.