There are several good guide books on RVing on the Baja, I think the Church's do the most up to date stuff but all are good to a point. With that said we have been in Mx since 2001 and have spent most of that time either on our boat or in the trailer on the Baja and in the Sea of Cortez. Will send you a PM with phone number in case you would like to talk a little.
In answer to some of your questions, many fjolks like to stage at Protero campground about 6 miles north of Tecate. It's a nice San Diego county campground close to Tecate so you can take care of any visa paperwork and get a full tank of cheaper fuel before actually crossing the border in your rig. The actual crossing fwill only take minutes but suggest you plan on early AM departure t o avoid Tecate traffic and to make an early arrival at San Quintin. While there we like the El Pabellon Trailer Park located at KM 16/17 just south of San Quitin. It's on the beach with lots of good beach walking and local fishermen to trade with. Our next stop is generally Rancho Santa Inez in Catavina, makes for a short day but breaks up the otherwise long day to Gureo Negro. Campground is about 1/2 mile off the highway and basically just a large field but very quiet with lots of good hikeing. Next stop is Guerrero Negro, we like the Maalarrimo Restaurant, Motel and RV Park, it's on the main street on the right as you enter town. Good Restaurant and easy in-out RV park.
You can make it to Santa Rosalia the next day but I suggest you plan on stopping at San Ignacio, look for th Rice and Beans RV park sign as you enter town. This is a neat little Mx town with a high desert lagoon to visit and your real first opportunity to spend time in a town square and meat some of the locals. The other real reason is so you can get a decent start to the next day as this will be hardest part of Hwy 1 to deal with. the grade going down to Santa Rosalia is very (as in VERY) steep. However nothing to worry about just check the brakes before starting down and take it slowely and enjoy the view. We do it in 1st gear, exhaust brake on and 10-15 mph.
Have never stayed in Santa Rosallia with the RV but have been there many times on the boat. Really neat town with lots of history but what ever you do don't leave town without trying the hot dogs across the street from the church. Anyone can direct you to the church, it was built by the French and designed by Eifle (sp?), same guy who did the tower!