Baggage YYZ-IAD-RUH on UA and SV

Hi

My wife will be flying YYZ-IAD on UA (Y) then IAD-RUH on SV (J) (6 hours connection)

2 question:

1) Will UA agents at YYZ check her bags straight to RUH or will she have to collect them at IAD and check-in again with SV ?
2) I assume she will pay for the bags as per united policies but as she is flying the first leg on Y will she have to pay extra for the SV flight?

Thanks for the help

Vagus