Will insert and update wait while a table is being vacuumed?
The documentation says the following:


  ROW EXCLUSIVE
  
  Conflicts with the SHARE, SHARE ROW EXCLUSIVE, EXCLUSIVE, and ACCESS EXCLUSIVE lock modes.
  
  The commands UPDATE, DELETE, and INSERT acquire this lock mode on the target table (in addition to ACCESS SHARE locks on any other
  referenced tables). In general, this lock mode will be acquired by any
  command that modifies data in a table. 
  
  SHARE UPDATE EXCLUSIVE
  
  Conflicts with the SHARE UPDATE EXCLUSIVE, SHARE, SHARE ROW EXCLUSIVE, EXCLUSIVE, and ACCESS EXCLUSIVE lock modes. This mode
  protects a table against concurrent schema changes and VACUUM runs.
  
  Acquired by VACUUM (without FULL), ANALYZE, CREATE INDEX CONCURRENTLY, and some forms of ALTER TABLE.


There is no conflict between the two lock types involved.  This means that neither INSERT/UPDATE blocks VACUUM, nor the other way around.  This means furthermore that your queries should succeed without timeouts.  Most probably the I/O activity of vacuuming won't do you any harm.