It was mentioned earlier in this thread that there are no pictures on the PA park sites while on RA. This option is available to each site that is on RA. It may cost the state more and maybe PA elected to not use this option? I just know it is available through RA. Check other parks in other states on RA and you will see pictures on a lot of them.
The restrictions on each reservation is made by the park not RA. Where I am hosting now we can not make any future date reservation for this park over the phone, but if the camper is physically here we can not only check them in for any site in the park even if they did not have a reservation, we can make future reservations for any site in this park, but they do have to physically be here for us to do it.
Concerning weekend reservations: The park I am in now requires a two night reservation for any arrival on a Friday or Saturday. Again, this is a park restriction not a RA restriction. We don't have an override on this for a walkin either. This is just the way this park manager wants it and RA administers this requirement.