Transportation from Heathrow to Central London and back

No, Yes, and Yes. HeathRow is in the fifth or maybe sixth zone so it would be outside your travelcard.

Heathrow is in Travelcard Zone Six if you use the Underground. The faster Heathrow Express and Connect rail services to Paddington are not covered by any Travelcard at all.

If your travelcard is still valid on the day when you travel to the airport, buy an extension ticket from Zone 2 to Heathrow. As said before you cannot use it on HEX and Connect services.

The more I read and become familiar with how the system works, maybe we won't buy a 3 day travelcard. I honestly think we'll do more walking. We'll take the tube from our hotel to the city and walk to most sights from there and take our river cruise to the Tower of London. I can think of 3 times we might take the tube, except for the airport, of course. The Heathrow Connect sounds tempting in that case, being able to see some of the sights on the way in, instead of being underground. Say, we want to buy a paper ticket to the Westminster Tube from Lancaster Tube and then back one day; the next we might want to go see the Abbey Road Crossing, so we buy a ticket from Lancaster tube to St. John's that day, leaving one other excursion for the third day - maybe to the British Museum and British Library. I've been reading all about Rick Steve's walks, and that sounds like something we'll want to do. Then (if thought it's a bit pricey), we'll ride the Heathrow Connect to and from Heathrow. Does all this sounds like a plan?

For single fares on the tube an Oyster card will be more economical, basically, to encourage their use, TfL have made a single journey ticket more expensive than a single journey if you pay by Oyster.

A single tube ride in zones 1-2 is £4 if you buy a ticket or £1.60 if you use Oyster. Another advantage of the Oyster is that if you make more than one journey a PAYG Oyster will cap the price at 50p less than a one day travel card.

Another piece of advice, you mention the Lancaster tube stop, it's name is Lancaster Gate. I know it's common in the US to drop the word Street, Avenue, Square etc. from addresses but we don't do that in the UK. If you are buying tickets or taking taxis/asking for directions etc. you should make sure to use the full name of places just to make sure you get what you want.

There's, the almost certainly apocryphal, story of the American tourists who buy a ticket to "the Liverpool station" and end up 300 miles away from where they intended.

Thanks for the tips! I appreciate it very much

I would agree with Peter's suggestion. Get an Oyster card at Heathrow and put some pay-as-you-go money on it. Perhaps put 15 GBP on it to start. You can use it for the trip from Heathrow and trips in London. If you need to add more money, then you can do that. I think that you will find that you will use the tube more than you think. London is a big city.

One other comment regarding your note that the Heathrow Connect is above ground as opposed to the tube. The tube from Heathrow is above ground until you reach Earl's Court. However, there is not much that is particularly scenic along this route. I generally take the tube from Heathrow. It is a lot cheaper and unless you are staying right at Paddington, I find it does not take much longer.

Just my 2 cents, but I would start with 10 pounds, for 3 days...we were there for a week and put 15 on and still had a ton left...we had intended to cash it in on our way back home through London, but never made it back to London because of problems with the Chunnel...

The only sight along the railway from Heathrow to Paddington is the Trellick Tower, if you're a Brutalism fan.

Thanks! I had no idea. I guess I thought the trip would be scenic! Ha!