Dual Blade questions and worries

hey there. Im afraid something might be wrong with my Dual Blade. Im worried that his SP might be screwed up, and some other questions about how DBs work.

Right now at lvl 63, my SP distribution looks like this;

1st;
16/20 Nimble Body
3/10 Disorder
10/10 Dark Sight
0/20 Double Stab

1st+;
20/20 Katara Mastery
0/10 Triple Stab
20/20 Katara Booster

2nd;
20/20 Self Haste
30/30 Fatal Blow
20/20 Slash Storm
2/20 Sadow Resistance

2nd+;
1/5 Tornado Spin
0/20 Flashbang
20/20 Flash Jump

I got to lvl 55 when DBs were first released. I used the option to start at level 30, which is why I didnt take any points in Double Stab or Triple Stab because I already could get fatal blow and slash storm. Maxed booster is weird, I know. Back when I made my Db I didnt have any place to put the points into. What is the ideal DB sp build at lvl 70, and going past that level? I can't find any guides for Dual Blades post big bang.

My other questions pertain to Tornado Spin. This ability really confuses me, but ive been trying to use it in game. It is sort of like Rush and Final Charge put together. Im supposed to press a direction key twice, and then press my attack key to make it work?

How exactly does it work in conjunction with Flying Assaulter?

I saw this line in the Flying Assaulter skill description;
Lv.10 effect: Lv.20 Tornado Spin can be used with Lv.10 Bloody Storm

What does that mean? Does that mean I can use Tornado Spin, Bloody Storm, AND Flying Assaulter in one go?

Do I have to have level 20 tornado spin to use Tornado Spin with Flying Assaulter? Will my botched SP distribution mess this up?

Can I use level 20 Slash Storm with flying assaulter, or does it HAVE to be bloody storm? And if it has to be bloody storm, does it HAVE to be level 10 for me to use it in conjunction?

Thanks for the help guys. I know these are all questions, but this was thief-exclusive so I didnt post it in the Q/A forum.