Okay... I have tried all of your recommendations and I'm back to square one.

I followed very throughly the instructions on document 1012307.6:

1) Create new user (user-b)
2) ALTER USER user-b QUOTA 0 ON TABLESPACE tblspace-A

3) REVOKE UNLIMITED TABLESPACE from user-b

4) ALTER USER user-b DEFAULT TABLESPACE tblspace-B
QUOTA UNLIMITED ON tblspace-B

5) Tested create test table on tblspace-A (did not allow)
- received ORA-01536 instead of ORA-01950

6) Tested create test table on tblspace-B (okay)

7) Performed Import
Results: with RESOURCE priv and without doing step 4
it imported back to tbspace-A
Without RESOURCE and step 4, it loaded into
correct tblspace-B but failed with the following
errors:

After various combinations of removing privileges (RESOURCES) and removing tablespace allocation, I was able to load into the appropriate table space but the import failed first with "IMP-00017: following statement failed with ORACLE error 2270:..." and after reimporting with options ROWS=N, IGNORE=Y, it failed again with error "IMP-00017: following statement failed with ORACLE error 2264:"

Please help?