1. fields are name and adress of the vendor, reconcilation 
account details, payment terms, sort key, bank details,etc.,

2.It reconcile the balances between General ledger and 
subsidary ledger. Its not possible to post the entries to 
directly in this account

3. There is no flexibility (in my opinion).

4. i dont know.

5. There is a block indicator check box in the gl account.

Ans.1) normally when we created any vendor the required 
field is account froup (This group we define  when we 
created master data for vendor 
) than we need a reconcilation account and vendor name, 
company code is very important and than fill all the 
information of vendor.

Ans.2)Reconcilation a/c in normally required when we 
created vendor and customer bcoz subledger( sundry debtor 
and sundry creditor) goes to the reconcilation account .No 
we can,t post directly in  the recon accnt.

Ans.5) If u want to block g/l accounts than block chart of 
accounts.