i have been shooting lf paper negatives for quite some time now. i shoot 4x5, 8x10 & 5x7 paper. iso 6 is a good place to start, but depending on the type of light and the kind of day it is, you might be right on, or way off with your light meter reading. if you have a blue filter, make your reading through that, and you will get more conistant metering results.
i don't usually use rc for my negative, mainly since i want to make an archival print, i want to make an archival negative as well. i have used double weight paper as well as single weight, i like to work with single weight the best - its easier to handle in the developer and easier to print. don't forget to trim the edges a little bit, film isn't really 8x10 &C but about 1/32" less.
one thing you can do is wax the paper to make it translucent, as jdef suggested. you can use parafin or beeswax - it does the same thing that a brown-bag does with fried food ... if you want to retouch portraits or lighten shadow areas, or even remove phone/electrical lines "the olde fashion way" you can do it with pencil on the back of your negative. it takes a little bit of practice and is not as critical as retouching on film. paper is forgiving and will block some of your pencil strokes. if you have ever retouched film with leads, you probably know how difficult it is to get the right "stroke" that blends and doesn't enlarge.
the way i have been processing my paper negatives is kind of out-there. rather than just doing a paper developer with the correct dilutions for making prints, i adopted a technique using dilute partially exhausted developer to give a little more control and a water bath so when the tones start coming out, you can put the image in the water to slow down development & back in again to speed things up. i use ansco 130, but i am sure any paper developer will work fine -
if you make a negative that is nice and contrasty, and looks exactly like you want the positive print to look, it will be washed out when you make your contact print. the ideal paper negative is neither thin or contrasty, but just in between