Goods Recipt without Purchase Order

Hi Experts,

Can any one Explain me the Process of Goods recipt without Purchase order.

1) What document type i need to select ?

2) Does i need to process MIRO for these ?

3) If it is a Usual material which i previously procuring throgh purchase order, How it reflect in Stock ?

4) Where can i find the difference of the Material which has purchased through Purchase Order and without Purchase Order ?

5) Does it affect usual stock ?

6) How to follow Vendor Returns for this ?

Plz Plz Give ur Valuable inputs on this.

Best Regards

Javeed