E: QMC questions
In general, yes. Although there may be cases where using different pseudopotentials may be of little importance, this is not true in most situations. CASINO requires the pseudopotential on a grid, and quantum chemistry codes tend to require them expanded in Gaussians. The online library has the pseudopotentials in both formats (with the latter done specifically for GAUSSIAN, CRYSTAL and GAMESS). There are also some notes supplied below the table which you should read.
Have a look in the CASINO/utils/pseudo_converters directory for utilities that convert pseudopotentials formatted for other non-Gaussian codes into the correct format for CASINO. Utilities are currently available for ABINIT, CHAMP, CASTEP, PWSCF, and GP.
You shouldn’t, see D1.a. If you generate all-electron orbitals, you should run all-electron QMC calculations. Notice that the scaling of all-electron QMC with atomic number is problematic, you should almost always use pseudopotentials to simulate everything but first-row atoms.