Okay guys... here is the short answer...
1) Cross at Tecate Use I-5, I-805 south then Hwy. 94 east (border here is closed after 11 pm).
2) No visa (called a tourist card/ FMM) is needed for trips in Northern Baja for up to 3 days. A free FMM is available for up to 7 days, obtained at the border and they must have a PASSPORT to issue it to you. A ~$23US one is good for 180 days.
3) Returning to the USA, a PASSPORT is prefered, but NOT mandatory. Birth certificate and photo ID is acceptable as proof of citizenship.
4) Jacume is just across the border from Jacumba, CA... so you are not 'deep' into Mexico. You do need to cross at an official border, however. Tijuana, Otay Mesa, Tecate, Mexicali, Mexicali East and Algodones (near Yuma) are the borders into/ out of Baja.
Want more Internet Baja? ... the most active Baja forum is http://forums.bajanomad.com several Nomads are also here on TW. My Baja web site may be of interest, since my Tacoma is featured in many of my trip photos! http://vivabaja.com