What are the main characteristics of high reactive power RF capacitors?
What is Capacitor Dissipation Factor (DF)?

\$\mathrm{DF}\$ is dielectric ratio of power lost to power stored and is the inverse of Quality factor (\$Q\$). Power dissipation results in self-heating and due to common  thermal resistance of dielectrics. 

Capacitors can be specified in many ways.


\$\mathrm{DF}\$ usually for 120Hz to 100kHz    
\$\tan\delta\$ for PCB dielectric, RF caps etc..
\$\mathrm{ESR}\$ @ \$f\$ (for low \$\mathrm{ESR}\$ types)   
\$Q\$ for RF types    
\$\mathrm{VAR}\$ (VA reactive)  for grid or motor power factor correction.     
Ripple Current (Amps) for e-caps and plastic film caps


DF also can be computed/converted many ways.

$$
\mathrm{DF} =  \tan{{\dfrac{1}{Q}}=\tan \delta ={\frac {\mathrm{ESR}}{\left|X_{c}\right|}}}=\mathrm{ESR}\cdot \omega C 
$$ 
where \$\omega=2\pi f\$.
Also 
$$
\mathrm{DF}={\text{Power Factor (PF) if }}\mathrm{DF}&lt; 0.01 = 1\% 
$$

DF examples

, 1% or more Ceramic general purpose high \$\mathrm{D}\kappa\$
, 0.1% NP0/C0G Ceramic low density
, 0.1% to 1% typ. Aluminium Electrolytic
, 0.05 %@ 1kHz Polypropylene (PP) e.g.    

With millions of variations in cap specs and costs, this is just a small sample.

 Answers


Ceramic caps with high \$\mathrm{D}\kappa\$ change with bias voltage , therefore have some hysteresis  but low \$\mathrm{D}\kappa\$ C0G/NP0 types do not (negligible but perhaps some).     
PCB epoxy has reasonably low \$\mathrm{DF}\$ but Teflon and ceramic are much lower. They also have large copper heat radiators so can dissipate more heat (1W/sq.in.). There are many grades of PCB materials.