How do I wrap around and start from the beginning when I have reached the end of items in a helm buffer?
(setq helm-move-to-line-cycle-in-source t) should do what you need, the option's documentation is
helm-move-to-line-cycle-in-source is a variable defined in 'helm.el'. Its value is nil
Documentation: Move to end or beginning of source when reaching top or bottom of source. This happen when using 'helm-next/previous-line'.
left("helm-previous-source") can always cycle all sources, right or C-o ("helm-next-sources") can cycle all sources when there is no a dummy source.