If they do this through Jewish Agency offices abroad before they arrive to Israel, they can come to Israel with a permit from the Jewish Agency, which will expedite the whole procedure. If you are already in Israel you should go to the local Aliyah information center with proof of your Jewishness. The B1 is the status give by the Ministry of Interior to who wish to work in Israel prior to changing their status to Temporary Resident, Permanent Resident, or Immigrant. From the Ministry of Interior it is up to one year, but it takes up to 2 months to get the work permit. From the Information Center it is for 6 months, and takes about 10 minutes if all the information is correct.
Renewal is more problematic than the original visa.
The onus is on the individual to find work. There is no longer any reduction. In other words, if you have been working with a B1 visa for 9 months and then made aliyah, you will have 2 years and 3 months of customs rights rather than 3 full years. However, if you leave the country, thereby cancelling the B1 visa and then make aliyah either from abroad or by returning to Israel on a regular tourist visa and then applying from here, you will retain the 3 full years. In any event, if you worked on a B1 visa for any amount of time over 2 years, and then made aliyah directly, the Customs Authorities will still grant you one full year of rights after changing your status to oleh.