question about BW 3.X updating method in infopackage.

Hello expert,

for BW 3.*, in infopackage there are several updating method to choose from.

for method "PSA and Data Targets/InfoObjects in Parallel (By Package)" and "PSA and then to Data Target/InfoObject (by Package)", global data do not exist when uploading data from PSA to data target, but for method " Only PSA", the global data is kept as long as the process with which the data is processed is in existence.

so my questions are:

(1) if there is no global data, I still want to do some processing for global data, I can save those individual data package into internal table . and start to process global data on this internal table, is that right?

(2) how to choose different uploading method as method "PSA and Data Targets/InfoObjects in Parallel (By Package)" and "PSA and then to Data Target/InfoObject (by Package)"? I don't think first method is parallel loading, it is still serial by data package. all those methods are only for parallel loading by partition in PSA, am I right?

(3) which one is performed best in performance perspective?

Many Thanks,