You shouldn't really worry about it getting hot on the outside, it means that the fans are doing their job. You would rather have all of that heat on the inside? Mine makes the wall behind it go warm after an extended period of use. People can easily forget that your model of PS3 has a 90nm CPU running at 3.2Ghz (go look at a Prescott Pentium 4's cooling solution), XDR memory @ 3.2Ghz, a 90nm GPU at 550Mhz internally and DDRIII @ 700Mhz.
What you need to worry about is when the machine cannot get the heat out, it's then that you will have problems. However, dust on the fan can make it underperform and thus make the system have to ramp up its speed higher than it should have to. On the highest fan speed (when the machine is under heavy load), yes, the PS3 can sound like a helicopter just like my old Prescott P4. All of this is controlled by the PS3 through temperature sensors inside it. If it does get too hot inside and it cannot ramp up the fan any higher it should turn itself off rather than letting a game freeze.
As for your problem with LBP, I have no idea. That could be anything from a bug to a hardware defect to a badly pressed disc.