What are the appropriate storage conditions (temperature, duration etc.) for Extracellular vesicles (PCR analysis) for biomarkers miR-16p and 21p; 1. pre lysis and 2. post lysis?

What is the appropriate Extracellular vesicle (isolated from cell culture and plasma) lysis conditions for miR 16p and 21p PCR analysis, if someone is aware of?

Is there any way to detect atmospheric RNA/RNAase contamination, especially when I am seeing miRNA 16p and 21p even in the unlysed controls?

What are some of the positive and negative controls for EV specific (miR 16p and 21p) PCR analysis?

Thanks in advance!