I have an Oyster Card from 3 years ago. Will it still work? Also if I am in London for 7 days, how much should I load onto the card? I will then be away from London for a week and then returning for 2 days. How much more will I need to load onto it?

It will still work. I used a five year old one again last summer. You don't need to load it for the whole week. You can load it at any tube station. And the entrance and exit turnstiles tell you how much you have left.

I'd load it w/ a 7-day travel card and a little Pay-as-You-Go ££ so it will be ready to go when you get back to London Then if you need to you can always add more PAYG.

Whilst it will work, what you can load onto it depends on if it's a Visitor Oystercard or not. If it is then you can only load cash - aka PAYG.

BUT if "I" is "we" and you want to do touristy things you need to research the 2-4-1 offers that you get having a paper travelcard bought at a National Rail ticket office

Is the visitor Oyster fairly new? I didn't realize there were two different kinds, though my last trip was in 2009. Is there any advantage to ordering the visitor Oyster ahead of time vs just getting one at Heathrow?

>>Is there any advantage to ordering the visitor Oyster ahead of time vs just getting one at Heathrow?<<

Not AFAIK. The visitor version are pre-ordered from home. I really don't see any advantage to them.

Thanks, janis - that's what I was thinking. Unless the "resident" Oysters now need a photo or something, to me it sounds like just one more thing to keep up with when I'm packing.

Nope, no benefit to getting them in advance.

Thanks, jamikins!

I'm just wanting to know if the OP's moniker is a reference to a beach locale near Sydney or an indicator that she was an athlete for the defunct German Democratic Republic.

Note also what Alan said: if there's more than one person in the traveling party, your Oyster card will end up costing you a fortune - there are a ton(ne) of discounts available, specifically two admissions to a given attraction for the price of one - if you have a paper travelcard.