Hey Roya,
1) I presume you have already called the lbfluid command to create the fluid. In this case the setting of a temperature using the lb thermostat should provide HI given reasonable parameters.
2) I find with lb it is often necessary to use kill_particle_motion just prior to initiating the lb fluid. If that doesn't work I would try with thermostat lb 0.0. If that still break try using a tiny friction: "lbfluid friction 0.0000001". The thermostat lb 0 just kills fluctuations while the friction being tiny should essentially kill the particle-fluid interaction.
3) You can print out the pressure of individual nodes using lbnode x_index y_index z_index pi or lbnode x_index y_index z_index pi_neq, which gives you the equilibrium and non-equilibrium part of the pressure tensor on that lb node. This will however be quite slow if you call it a lot but unfortunately an lbfluid print pi is not available (at least it's not in the user's guide).
Hope that helps,
Owen