(1) Yes, Jeddah was also considered a meeqat by scholars.
(2) After performing umrah, there is no dum if one passes by meeqat or Haram boundary while returning. It is necessary to wear ihram while entering into Makkah as mark of respect for Ka’ba. There is no need of ihram while returning.
Allah knows Best!
Darul Uloom Deoband