This is super old now, but I figured I'd chip in. There are two different questions here in the context of a switch hit:
1) What about wides?
2) What about LBWs?
For the purposes of wides, the switch-hitting striker sacrifices the benefit of the leg side bowling limit. In other words, he effectively has two off sides for the purposes of calling wides. This is established, IIRC, in the playing conditions for limited overs games.
(Edit: I recalled incorrectly - it's just the way Law 25 is applied in that context:
The umpire shall not adjudge a delivery as being a Wide,
(a) if the striker, by moving,
either (i) causes the ball to pass wide of him, as defined in 1(b) above...
For the purposes of LBWs, the off and leg sides are determined by the striker's stance at the moment the ball becomes live, as noted in the previous answer. The switch hit does not affect that, so a ball which pitches outside his now off-stump, in a switched stance, would be deemed to have pitched outside leg and therefore be ineligible for LBW.
It's also worth noting that a switch hit is determined by the striker's GRIP, not by his feet. A reverse sweep is not a switch hit.
Also worth noting that the striker can't change back ito wides. Once he's given up that leg side protection, changing back to his original stance will not get it back - it's two off sides for the purpose of wides, and will remain that way until the delivery is complete.