Sorry I have been very busy the last few days but I did want to respond to see if I can help give you some things to think about
I agree with the others posted that you would benefit from joining a club and going to a workshop with this tree to get guidance from more experienced folks. I will try to answer your questions to the best of my ability
What are the possible styles for this tree?
Looking at this photo. I see a bunch of branches low down on the trunk above the pot and a pretty wide gap between the next set of branches
You could consider chopping the tree just above the lower foliage and picking a new leader to grow into a informal upright or slanting style.
You would do this in stages, chopping back the trunk over a few years. You never want to remove more than 30% of the foliage off a pine in one year.
How would one go about actually bending and manipulating such a thick trunk line?
The trunk below the first branches wont be able to be bent easily and would require hollowing out the trunk to reduce mass and get it to bend. But honestly, why would you want to do that? It has great movement already and you can build a really nice tree using that. Above that could possibly be bent with raffia, a backbone wire and other wire wrapped around that but the gap between branches as stated above will probably detract from the usefulness of doing that.
Should I clean up crotch growth?
It depends. Could that new growth be used to build better branches with foliage closer to the trunk and better ramification.
As stated by Japonicus, we generally want to keep inner foliage and build branches from there and eliminate branches that have growth far away from the trunk and give a pom pom appearance
Should I eliminate the whirling? If so how many is it ok to remove?
Yes you should eliminate extra branches coming from the same point but do it slowly, like a couple at a time each year because you will probably be doing this at more than one point along the trunk and you dont want to remove too much foliage in one year as I said above. So doing this over successive years would be best. For example in this picture:
![EB27202B-D94D-4F8C-B9CD-6A5191B0C5D6.jpeg EB27202B-D94D-4F8C-B9CD-6A5191B0C5D6.jpeg](https://www.bonsainut.com/data/attachments/491/491938-1d721b7ac1c052f198f923ac9c5c15de.jpg?hash=HXIbesHAUv)
I would remove 1-3 of the largest branches here. Why the largest? Because those will be the first ones to cause bulging at that area as the tree tries to bulk up to support the larger branches. You have one right above your fingers that is a small one but has a ramification very near the trunk. Without seeing all the options, I would try to keep this one because it already has some ramification close to the trunk.
Yes always use cut paste
If you use cut paste, you shouldn't get much sap run
I wouldn't right now. Because you could probably do some major pruning in late winter.
Also as stated above, please educate yourself about the differences in treating Japanese Black Pine (2 flush pine) vs Japanese White Pine (single flush Pine). They are treated very differently and if you treat this JWP like a JBP you are going to kill branches and maybe the tree.
If you look at this picture:
You have a nice little branch here but there are wide internodes (gaps between areas where smaller branches are coming off the larger branch). If this were a branch I wanted to keep. I would cut it right above the second little branch and then wire that out to be the new leader for that branch to build more foliage near the trunk. However you would have to be careful that any branches above that one didnt shade the new little branch so it gets the sun it needs to grow. So again this is another example of how you should cut back the tree in stages to get what you want to accomplish.
I hope this helps.
I think this could develop into a really nice tree if you take the time to do it correctly.
Good luck with it