There are different SWA Visas. The personal regular RR plus and RR premier cards and the RR premier business card. All of them have annual fees but you get RR points on your anniversary date that almost offset the cost of the card.
Many people will get both the personal and the business cards so that they can get the bonuses for both. Those bonuses get you almost all of the way to a companion pass. The companion pass will allow the RR member to name someone who can travel with them for free when they book a flight for themselves. Timing your applications so that you achieve the required number of points early in a calendar year will ultimately result in a year of free flights for your companion. The bonus RR points can be used to book travel for anyone that you care to spend themm on.
There is no problem booking with both RR points and cash, but you have to book rewards tickets separately from the cash tickets. Cancellation rules for rewards tickets and cash tickets are different. The big difference is that when you cancel a ticket booked with RR points, you get your points restored to your account. when you cancel a cash ticket, the ticketless funds are not refunded for WTGA fares. Not only that, bu only the person for whom the original ticket was purchased can use those funds and they will expire one year following the date when the ticket was purchased. That means that travel must be completed by that date, not that you have until that anniversary date to book the new flight.
Since the RR member earns points for cash flights, it can be a good idea to book the member's flight with cash and then pay for other flights with points.