as far as i know, the forest service has dismantled the bridge with no plans for rebuilding it. last time i was through there (august '06), the remains of the bridge were stacked on the south side of Swamp Creek just off the portage trail.
we singled portaged (and we're all in our 20s and trip regularly) and i'd say it's about a six hour trip. even if you normally single portage, expect the 400+ rod portage to take a bit (we took one short break). the river travel, with all the twists and turns, is over 5 miles of paddling. given that you'll paddle slower than usual with all of the back and forth, i'd say at least three hours for the paddling alone. add 2+ miles of portages and that will be an hour or more of walking, not including landing and launching and stops, etc.
i'd say figure 6 hours to get to Stuart. but maybe less. i would start early -- there aren't many sites on Stuart, but it does seem to be a somewhat popular hub lake (between Agnes and Iron). in august 2006, we got there early afternoon and took one of three remaining sites. in july 2004, we got there late afternoon and took the last site available (the one on the north-central point -- a passable site, but not great). the northern-most site (on the west shore of the NE bay) looked nice, but we claimed the island site, which was very nice.
also -- if you happen to fish, the eating-size walleye seem to go in groups on Stuart (and elsewhere). casting deep-diving rapalas from the non-shore side of the canoe, about 40 ft off shore, we easily caught many 12" or so fish. we also caught a 2 lb and 4 lb northern in the same evening.
the river flows north into the lake -- if the water is high enough, it makes for quite the falls at the entrance. if not, then the rocks are impressive, even with the low flow of water. here is a shot from early august '06 (with low flow):