Rambler, yes you can get shingles again, and the immunization is useful even when you have had shingles in the past. I am not aware of evidence that a prior episode places you at risk for recurrent episodes but in my experience I would say yes.
Nords, this issue is that while a strategy of "younger" immunizations is logical, it has not been studied well for safety and efficacy. Also, the risk of shingles is lower in the under 60 crowd altogether so there is less benefit in younger populations as a whole. So, it may be logical and beneficial to take it earlier, but an honest recommendation would be that we just don't know. OTOH, it would not surprise me to see the recommendation change in a few years to start at a younger age; for now that would be "off-label."