No
Yes
No
As I keep saying but not body listens (probably because ignorance is a bliss).
Extension of Continental shelf does not mean extension in the maritime boundary & by that virtue the Exclusive Economic Zone (EEZ). Continental shelf is the submarine landmass (seabed or subsoil). The sea above remains an 'international water body.' We have gained only the rights to exclusive exploitations of the land under that water.
Fishery too remains outside this purview. The UN Commission on the Limits of the Continental Shelf (CLCS) - body that has granted Pakistan extension of its continental shelf - says the following:
Article 77(1): The coastal State exercises over the continental shelf sovereign rights for the purpose of exploring it and exploiting its natural resources.
and then
Article 77(4): The natural resources referred to in this Part consist of the mineral and other non-living resources of the seabed and subsoil together with living organisms belonging to sedentary species, that is to say, organisms which, at the harvestable stage, either are immobile on or under the seabed or are unable to move except in constant physical contact with the seabed or the subsoil.
* Hence, the fishery in the granted area remains open to international exploitation.
The Article 78(1) says: The rights of the coastal State over the continental shelf do not affect the legal status of the superjacent waters or of the air space above those waters.
2. The exercise of the rights of the coastal State over the continental shelf must not infringe or result in any unjustifiable interference with navigation and other rights and freedoms of other States as provided for in this Convention.
* Meaning Pakistan has no control over the waters & air space above the given continental shelf.
About the question you posed browser. The Article 79 of the convention addresses the issue of 'Submarine cables and pipelines on the continental shelf' & I quote:
1. All States are entitled to lay submarine cables and pipelines on the continental shelf, in accordance with the provisions of this article.
2. Subject to its right to take reasonable measures for the exploration of the continental shelf, the exploitation of its natural resources and the prevention, reduction and control of pollution from pipelines, the coastal State may not impede the laying or maintenance of such cables or pipelines.
* Coastal State here is Pakistan.
3. The delineation of the course for the laying of such pipelines on the continental shelf is subject to the consent of the coastal State.
* Here we get the upper hand. Iran & India would need Pakistan's consent for laying of pipeline. But the pipeline would have to go through Pakistan's waters anyways. Dragging it around Pakistan's waters & previous continental shelf limit would still have been costly & painstaking.
4. Nothing in this Part affects the right of the coastal State to establish conditions for cables or pipelines entering its territory or territorial sea, or its jurisdiction over cables and pipelines constructed or used in connection with the exploration of its continental shelf or exploitation of its resources or the operations of artificial islands, installations and structures under its jurisdiction.
5. When laying submarine cables or pipelines, States shall have due regard to cables or pipelines already in position. In particular, possibilities of repairing existing cables or pipelines shall not be prejudiced.