I use thread specifically labeled for hand quilting. It's stronger. I use no longer than a length of 18 inches of thread at a time or else it gets tangled. My favorite size needle is 11 but there are smaller and larger sizes.
I also use a leather thimble b/c it's the only one I've ever been able to use. But again, there are many others.
As for the border you really need to measure it and then measure the repeat of the quilting stencil. It's nice to have all the corners the same. I would check Youtube- maybe they have a tutorial on that.
Good luck! I love hand quilting! :D:D