I think the tests are different for platform and on-board staff, but when I went last the tests were all done at the same time, I think there was only a minute or so between each test. It goes really quickly! The one recommendation I'd make is to make sure you wear a watch so you can keep a close eye on the time, as they don't tell you how long you've got left once the test has started and the limit comes up pretty fast (I can't remember how much time I had though, sorry).
For the interview, just stay clam. Make sure you re-read your application form a number of times before you go on Tuesday as they'll probably ask you to answers these same questions in person, they may also ask you to further elaborate on the answers you have given. You could probably give new examples if you wished, but your best to stick to the ones you put on the application form, as they're presumably the best ones you have.