london oyster card

What type is your contactless credit card? Some seem to work better than others, Amex is the most likely to work.

If you are not using the card directly, but just using it to buy an Oyster card then there is no issue.

You can communicate while in london on vacation 8 days with email or facebook social media if you have wifi at your hotel

Yes, you can buy an Oyster card with your U.S. credit card. Make sure you alert your bank that you will be traveling to the UK or they might freeze your card when trying to use it.

Sim cards vary in price depending on what services you get. Try to find a Carphone Warehouse location. They sell sim cards from different companies and will help you find the best card for your needs.

If you can get wifi at your hotel, services such as Skype and WhatsApp can help you communicate. If you have Apple products you can Facetime.

When you say "best way to communicate while in London" do you mean to other locations on your trip or back home?

Many 'tap' credit and ATM cards (not all) will charge a foreign currency exchange fee each time you use the card, making each Tube or bus ride more expensive rather than less. Buy an Oyster.

Apple Pay and the Android equivalent can also be used at the turnstiles in lieu of an Oyster card.

Individual trips, unless it is your only one for the day/card combination, are not sent through individually. They are batched together and sent for each day, so only one fee from your bank a day.

For a SIM, we pop into an "EE" (Everything Everywhere) store. Last time I think we paid 20.00 GBP for the SIM, 30 days of services, 4GB data. It was more than enough for two weeks in the U.K.