Others will likely be able to chime in about other aspects, but I have a few tips potentially!
Welcome to the London housing market. Renters have far fewer rights here than the US, and especially California. As you are new to the UK and renting overall, I would highly suggest finding a flat share situation. A flat share will likely have a lot of things set up already - like a tv, cooking utensils, furniture, etc. It can also help you along with getting to know the city and meeting new people by living with others who already know the area. There are some fantastic flat shares about in great houses - check spareroom.co.uk to see what is available.
Also - learn about public transport. If you don't want to live in E14, you don't have to. Figure out how much you want to spent per month on rent and how long you want to commute and go from there. The East End is only now up and coming, there are better places to live more central in the city or in the inner suburbs if you want more space and trees etc. If you hit the housing thing hard you could maybe avoid staying in a hotel for longer than two weeks. Alternatively, try airbnb.com for cheaper stays in people's apartments.
For banking - good luck. This is a major hassle for expats. Get documentation from your company that you are employed by them. You can try to take that with you to a bank, along with your passport and visa, and see what type of an account you can get. IF one bank turns you down, try another. Yes, its lame and archaic, but that is how it goes here. Alternatively, I have seen a company that offers to set these things up- I think its 1stcontactkickstart.com. I haven't used them, but have read of others who have and thought it was decent value for money to skip the banking stupidity. If you feel this overwhelmed, you may want to give that a shot.
When you get here, make sure to get an Oyster card for transport. You can buy these at plenty of newsagents that have the sign in the window. You can also order them ahead of time to be delivered to your US address if that is easier.
Taxes I have no clue - lol. You may need to find specialist advice for that issue.