[OSPF] OSPF GR query

Hi 

I have query related to Strict LSA Checking in OSPF Graceful Restart.

Consider this scenario:

- Two Routers R1 and R2, connected with a Broadcast network.
- Where R1 is a DR and R2 as DR-other
- Now R2 wants to perform GR and R1 agrees to be its Helper.
- Now after restart R2 will try and form adjacency with R1.
- Lets say that R1 and R2 had reached Exstart state. Now at this time
another router R3 joins the network.
- This router R3 will effect the contents of R1 LSDB. 
- Now if Strict LSA Checking is enabled, R1 will quit from Helper mode.
- After quiting R1 will recalculate DR/BDR and will reoriginate router
LSA and network LSA. 

Considering above scenario, my doubts are:

- How will R2 come to know that its Helper has quit ?
- When will R2 exit GR ? 
- As the NBR state had reached to Exstart before R1 exited, will state
be back to Down and   
  the adjacency formation will start all over again, once R2 exits GR ? 

Regards
Aamir