As you found yourself, official information is now online (bolding mine):
Inbound flights to the UK from Turkey, Lebanon, Jordan, Egypt, Tunisia, and Saudi Arabia
You must put all phones, tablets or laptops in your hold luggage if they are larger than:
- 16cm in length
- 9.3cm in width
- 1.5cm in depth (or thickness)
For example, you can take an iPhone 7 Plus, Samsung Galaxy 7 Edge, Samsung Galaxy Note 3, LG G3 or Sony Xperia Z2 as hand luggage.
This also applies to:
- any items you buy at duty free in the airport
- connecting flights via these countries, even if your journey started elsewhere.
You can still bring hairdryers, straighteners, travel irons, electrical shavers and e-cigarettes as hand luggage.
Little official information is out so far and I cannot answer your question 1), but for 2)
you will not be able to bring your laptop in the cabin.
Source: OneMileAtATime on the topic, itself sourced on Tweets by Sky News.