I'm not sure what you mean by 'all inclusive transportation passes'. If you are referring to 'travel cards' in London, you buy those at NATIONAL RAIL STATIONS, but USE THEM on buses and the tube. They are good for 7 days (and you need to bring a passport sized photo for the free id card they make for them). These PAPER travel cards are also used to receive the 2-for-1 discounts for admission to some sites, and discounts at some restaurants and shops. You can check out the deals at this website: http://www.daysoutguide.co.uk/2for1-london If you decide to use this method, you might want to print out the vouchers for any deals you are interested in as booklets of them sometimes run out at the stations. You could purchase your travel cards at Paddington station upon arrival.
You can also purchase Oyster Cards from a tube station, which are really a payment method. You can 'load' Pay-As-You-Go (paygo) cash on these plastic and the Oyster will calculate the cheapest fare for the day based on your usage (they are good on buses and the tube), AND /OR you can 'load' travel cards on them. THEY ARE NOT VALID FOR THE 2-4-1 deals! You do have to pay a deposit for the card, but it, and any unused paygo cash are refundable when you turn it in at the end of your stay.
Getting from Heathrow to Paddington - you have several choices. You could purchase tickets for the Heathrow Express (fast but more expensive direct train), the Heathrow Connect (slightly slower, but a good bit cheaper train), or take the tube (least expensive, but slower. You would need to buy either a one time use ticket for the tube, or a one day travel day (use it only on the day of your arrival- giving you time to get the paper card later) or buy your Oyster card at Heathrow if you decide to use that method. Or you could use a 'hire car' service (like a pre-arranged taxi) or regular taxi (expensive). Times for these will depend on traffic conditions and they can be expensive.
If you are considering purchasing something called the London Pass, you should know that most people here believe that the 'travel option' that you can add to the 'London Pass' is NOT A BARGIN AT ALL. Many of us also believe that the plain 'London Pass' itself is not worth the expense, either. As one poster often says- YOU have to do the math.