the ap is not abandoned if you leave while it is pending, but were
maintaining h or l status at the time you depart and then return using a valid h or l visa. Once the ap is approved and you are in the usa after approval, it can then be used for subsequent travel.
If you return using a valid ap, you will be a parolee, evidenced by the i-94 you receive. You cannot hold "dual status".
You will
not be in h1b
status, but under a legacy uscis memo (the cronin memo), you may continue to use the
employment authorization element of your valid h1b petition as long as you return and continue to work for the h1b employer. It does not alter the fact that you are a parolee, but does mean you do not have to use a separate ead.
A subsequent extension or amendment of the h1b petition will return you to h1b status, or you have the option to leave the usa and return using a valid h1b visa.
The points above are covered in this murthy
article and in this uscis
document (question 26 and addendum v).