mandatory/optional temp tablespaces and is everything in our databases BLOBs?

In general temporary tablespaces are needed for things relating to dynamic queries, sorts, dynamic tables ( i.e. joins ).  Being a DB2 person, a temporary table space ( system managed ) with very few pages is created when a database is created.   For example:

 Tablespace ID                        = 1
 Name                                 = TEMPSPACE1
 Type                                 = System managed space
 Contents                             = System Temporary data
 State                                = 0x0000
   Detailed explanation:
     Normal
 Total pages                          = 1
 Useable pages                        = 1
 Used pages                           = 1
 Free pages                           = Not applicable
 High water mark (pages)              = Not applicable
 Page size (bytes)                    = 4096
 Extent size (pages)                  = 32
 Prefetch size (pages)                = 32
 Number of containers                 = 1

I'd leave tablespaces like those alone myself, which is to say:  Take what the database management system gives you (mostly) at face value.   There are times to deviate, but probably not here.