Is it permissible for siblings to share the travel expenses related to their father's burial and retirement procedures, or to take them from the inheritance? And is it permissible for the eldest brother to reclaim a gift (mobile phone) he had given to his father before his death?

The phone you gifted to your father before his death became his property, and after his death, it became the property of the heirs. Your taking the phone back is considered a revocation of the gift, which is forbidden by Islamic law.

As for your return to bear the responsibility of the burial and retirement, if your travel was necessary for the rest of the heirs to receive their rights, you can ask them to share in the travel expenses. If your siblings are minors, nothing should be taken from their money except with the permission of their guardian.