1. reasonably short time, if you plan to get a US visa within one year or 2.
If over 180 days you must be subject to 3 years bar. But even less than 180
days, VO at US consulate can deny you if you stay a few months (<6) without
status.
2. if out of US >1 but < 6 years, you have a choice. Either to use a new one
(effective 10-1) with new 6 years limit, or use your first H1 for its
remaining years.
3. It's still yours in the same US bank/financial institute, subject to the
same rule as if you were in USA.