1. No, size doesn't matter - grace matters. 
 2. No, transubstantiation doesn't require an altar. 
3. No, it's not that organized. 
4. Depends, relics [cannot be sold](http://www.scborromeo.org/ccc/para/2121.htm) so they either have to be retired and buried or go to other homes.  It would be up to the local Bishop to deal with storage of the altar relic. But Canon Law says the altar can [lose its dedication](http://www.vatican.va/archive/cod-iuris-canonici/eng/documents/cic_lib4-cann1205-1243_en.html#CHAPTER_IV.)

> Can. 1212 Sacred places lose their dedication or blessing if they have been destroyed in large part, or have been turned over permanently to profane use by decree of the competent ordinary or in fact.

5. No - the relics are not necessarily related to the saint.  

Also, the degrees of relics are: 

- 1st degree 
   
  Any body part, hair, tears or blood from the saint

- 2nd degree

  Something that the saint touched or used during their lifetime. Saints like St. Maximillian Kolbe, who was cremated at Auschwitz, and St. Anthony of Egypt, who was buried in secret so his body wouldn't be fought over, only have 2nd degree relics.

- 3rd degree
 
  Something touched to a saints grave or over their corpse.