AusBonsai

I'm not sure what direction to take this tree so any suggestions would be much appreciated.

The majority of the thick branches go straight up which has ended up with obvious blunt tops. The cascading branch is something I'd love to make use of but as you can see from the photos it takes a really sharp turn to angle downwards. The sharpness of that bend is a lot more noticeable in person.

I feel like this tree has lots of potential, I'm just not sure where to take it.

The cascade branch may look interesting but I am not sure cascade would be suitable for a casuarina but you could try and then prove me wrong.
I would try to use that cascade branch as a first branch on an upright tree but you will need to remove the strong upright parts to get the horizontal section to grow and develop.
The blunt tops are only temporary after relatively hard development pruning. Some shoots on those will grow into branches then you can cut near those and there will then be a good transition from thicker to thinner. I think they are probably currently cut a bit too high so cross fingers and hope for a lower shoot to take off.
Bonsai is really a progression of cut and grow. You have only done the cut part and now need some patience for the second stage.

Thanks!

Looks like I really need to have a think about the style and be content with making a major decision and waiting to see how it develops.

In terms of the needles, should I be pinching them super short? At the moment so many of them are interweaving which is super messy and doesn't allow for a clear vision of its capabilities.

You need to be aware that casuarina needles are not actually needles. What appears to be a needle or leaf is actually the shoots of the casuarina. The actual leaves are microscopic. Take a look at the leaves and you will see they are jointed. At each joint there is a ring of tiny leaves (but you will need a magnifying glass to see them.
It is possible to break the shoots at any joint without upsetting the tree. You can also cut the stems anywhere. The internode that is cut will then die back to the next ring of leaves just as other tree stems die back to the node below the cut.
Just like other species breaking or cutting will activate new shoots to grow and therefore increase foliage density. So the answer is yes, trim log shoots to get a tidier look. It will take some time to really respond but if you continue to pinch and grow you can get there.

Same goes for longer branches. The pic shows someone has cut the upright branches quite long leaving a long, straight section with little taper and those 'blunt' ends. I would prune shorter and allow the replacement growth to grow out to the desired profile in several replacements instead of just cutting once.

Update: spent quite a few hours making tough decisions and tidying it up. Here's the outcome. Will be interesting to see how it looks in a year!

Good job. As new shoots extend you can break them (hold lower section between 2 fingers and use the other hand to twist and pull so the shoots break at a node) or even cut at this stage as any cut internodes will just dry out and fall off.
Development can be remarkably rapid if the tree has good conditions.

You should be able to find some examples if you search through the posts under natives - casuarina https://www.ausbonsai.com.au/forum/viewforum.php?f=56
Steven has some really good small sized casuarinas, Rory has done a lot of trials and R3 is currently developing some great trunks for casuarina bonsai.

Yes, that’s better. And the tree is in good health so should bounce back very quickly with lots of new shoots. As they elongate do what Shibui suggested. the twist and tear method gives great results quickly.

grant

Cannot believe it's been 11 months since I posted this!

Here's where we are now. I'm going for a windswept style which this tree really leans itself into (pun intended). Once the major branches are set I will focus on a pinch and grow strategy to fill it out.

My major gripes with the tree are the taper and lack of root base. I'm keeping the low shoots and rubbing out anything trying to grow above the first curve to help with taper, and I'm hoping the pond basket will help with some interesting roots.

Any suggestions or comments?