6wt should be fine Basti, as i imagine you would only be casting short distances and hence the 6 wt will load up the rod easily to allow you to make a nice cast with only a small amount of fly line out. As for the backing, you can use the 30 lb braid if you want, but you will probably under fill the reel, even after you've put the fly line on. If it's underfilled, the flyline will be in tight coils and may take a while to straighten out on the day that you use it (the warmer the air temperature, the quicker the fly line loses it's "coiled memory" - similar to a garden hose). Dacron is much much thicker than the braid we normally use, hence they're very very cheap. If i were you, i would save the 30lb braid for a 6000 size reel for gummys in WPB. Connecting dacron to the fly line is relatively straight forward using a nail knot. Flyline to leader can be done the same - or use a braided (loop) sleeve if you want to change leaders regularly. I find the braided sleeve much easier to use as i usually like to change leaders regularly depending on the situation.