I've used Combine ZP. It's free, and it works well.

Beautifully crisp focus even in double download. A fine shot. Placing that outdoors would make me very nervous, but the contrast with the live vegetation at the base is impressive.

Great shot. I've seen lots of D-C Cormorants, but never one with even a hint of a crest, so was impressed with this one.

What can Nikon do to beat that?

The amount of blurring in waterfall shots is very much a personal choice: some like just a little, some like a lot, etc. Go with what you like. Your first shot has great possibilities, though I agree with those who say reframe it to make the falls bigger and off-centre. I would also look for sharper focus in the surroundings in that one: in all the others it's really crisp, but a bit off in that one. My favourite is the last but one: nice sharp surroundings, nice blurry water, and interesting lines.

Your camera was rock steady: great. Just look at the lines: even at double download there is not a hint of a wobble. That's step one. Next look at the framing: do you want the whole burst, or zoom in on a part of it? Adjust as required, change lens if necessary. I use a 15-85 mm lens, and it gives me the spread I want. For focus, go to manual focus; before the fireworks start, focus on something the same distance away as the bursts. You may have to lighten your scene a lot to do this - go to manual mode, up the ISO to about 1000 or higher, aperture wide open, and focus on whatever you can see at the right distance. Once focus is set, put ISO back to 100 and aperture to about f8 or f11. For shooting, I like using the bulb setting with a remote shutter release. Having set the focus, ISO and aperture that I want, I can just press and hold the remote for a second or two, and the shot usually comes out fine (it's amazing how well you can do with a guesswork exposure - I just do a mental count - "one elephant, two elephant...") Check the rear screen after the first couple of shots to see if they are too light or too dark, and adjust the exposure time as required. If you are shooting RAW, you have good latitude for adjustments in post-processing too.

#2 is spectacular! A powerful argument for stacking.

Fine shots. How did you get all that depth of field? Must have been a tiny aperture.

Nice shots. Looks like a shasta daisy to me.

I meant "worth giving it a whirl"!!!

Thanks Ron: I thought it was giving it a whirl!

Thanks for your positive comment Murray - glad you liked them!

Thanks for looking and commenting Rich! Yes, give it a try.

Thanks OneShot1! Yes, I was getting myself all in a twist. Straightened out again now.

Thanks saxman71 for your kind words!