- What does the expansion contain?
- What are the different ways to play with it?
- How is each different from playing without the expansion?
- Is there anything else I should know about the expansion before buying?
The tickets work exactly the same way as normal, but it's a different set. They may also be combined into a single large ticket deck.
The standard bonus condition is longest route; the new one is most completed tickets. Both have the same value, and are often not the same person.
Since I've only played 1910 online, I can't speak to the card size issue.
Europe 1912, the comparable expansion for Ticket to Ride: Europe, likewise has replacement tickets and the most routes bonus, but instead of adding full size cards, instead adds a "depot" mechanism, which results in the trains deck being depleted sooner and more cards being out of play. While the tickets are not cross-compatible, the depots are. Since TTRE also has separate long route cards, 1912 also adds 6 more, to a total of 12.
I'll let someone else explain the expansion options, I just want to list the most important change.
Normal Size Cards