Hey mate, yeah I suggest getting braided wire. I got some from the sates. I'm using it on my current build too. I got I think 8ft first time round (4 of each) and this time I got 15ft of each (cheaper and can keep for next build) it makes a massive difference.
Was that you on my YouTube that asked? I haven't responded yet haha
I had to use different screws for the trem as the ones provided didnt fit properly. As there's no block underneath it is straight through the top only. Form memory I used a screw that was threaded all the way to maximise grip. The only thing I could think of to get more support would be drilling out the hole a bit and using some Dowell that extends to the back and flying it in place then fixing the trem screws into these.
My bar sits fairly high too, about 2 1/2-3inches above the face. You could probably bend the arm down about half way, but this could cause cracking to the coating. So unless you took it apart and bent it and re coated it I don't think there's much you can do except get a true bigsby... but that may also have different screw hole placements.
I didn't do any fret levelling or anything, I just sanded the ends a little when I was sanding the neck to smooth them off but haven't done and actual fret dressing.
Hope this is help in some way. Cheers