Multiple monitors in Lubuntu

Install arandr from the repos and you'll have a GUI to configure the multiple monitors. I don't know about the panel part of the question.

To establish dual monitors with LXDE, install Arandr from Synaptics. Arandr can set-up placement, orientation and resolution for each monitor. Before saving, set up the geometry of any horizontal panels. For a bottom panel across both monitors, align the bottoms of the displays; for a top panel, align the tops. A second horizontal panel can be only set-up on the display whose unaligned edge is outermost, since any extension onto the smaller display will be hidden. Otherwise, the horizontal placement and geometry in general can be achieved in the usual way. See http://lxlinux.com/#14 for more details.