LM4140: ESR requirement of Low ESR Ceramic Capacitors?

Part Number:LM4140

Hi there,

We use LM4140 for DAC REF2.5V. SCH as below.  On Datasheet page9 Figure24-26 shows a Cout's ESR value range for STABLE operation. 

1.We use high quality C1005X5R1A475K050BC 4.7u, which has a very low ESR as pic below. Not sure how to decide the freq because ESR changes with frequency .  Our system has DC/DC all worked at 800KHZ. 

So shou we serial one resistor R1018 with Cout ?  

2. I also need to ask,  there is mechanical stress relief action required on page 12 of Datashseet, is it necessary ? How much Mechanical Stress/Distortion will it affect its performance?  Is there quantitative relationships? 

Thanks!