Target load order is specified on the basis of source qualifiers in a mapping. If there are multifold source qualifiers linked to different targets then one can entitle order in which informatica server loads data into targets.
Surrogate key is a replacement for the natural prime key. It is a unique identification for each row in the table. It is very beneficial because the natural primary key can change which eventually makes update more difficult. They are always used in form of a digit or integer.