I just installed Notepad++ and tried it out.

> I haven't looked to see whether qq offers the same autocomplete options.

only if you type a round bracket so qq( will show qq/ won't

> while split( offers four formats,

Hmm, yes after typing ( it offered to permute thru 4 alternatives by clicking arrow buttons.

I couldn't find a key which helps permuting. Counterintuitively choosing between between the functions split and splice was possible with arrow-keys.

And I failed to expand one of those parameter options, be it as verbatim text or active snippet.

But they are kept shown while typing, when inside parens.

There is a hot-key C-S-Space to show those options again, but for arguments again only after an explicit open parenthesis.

DISCLAIMER: first time experience, I've never really worked with N++ before and might have missed some options.