I do a little clothes sewing; there's nothing to it really... follow the directions, make sure you cut out the notches or mark the dots; and then match those up like the patten says. Take your time, you'll be great.
As far as thread type. I use a polyester, it's not like it's a quilt, where you have to worry about the thread 'cutting' the fibers. I never paid attention to the weight of the thread, I just used a general thread in a color as close to the fabric as possible.
good luck, don't forget to give us a look at your finished dress