Past papers (with solutions) for TSA Oxford are here: http://www.admissionstestingservice.org/for-test-takers/thinking-skills-assessment/tsa-oxford/preparing-for-tsa-oxford/
A past paper for TSA Cambridge (with solutions) is here: http://www.admissionstestingservice.org/for-test-takers/thinking-skills-assessment/tsa-cambridge/preparing-for-tsa-cambridge/
Again, I think some time doing research will pay off. The UK is really not for somebody who is ‘somewhat undecided’. You study only the subject you apply to, and (to quote a History tutor at Oxford): ‘we want you to love our subject as much as we do’. Go read the subject pages for E+M at Oxford (here: http://www.ox.ac.uk/admissions/undergraduate/courses-listing/economics-and-management) and see if that looks like a happy 3 years to you. Go look at the Wharton program- does that look more or less happy to you?
“Also, is there any value in the trip I did last month last summer- staying in Spain for a month by myself and taking courses in Spanish, perhaps from a responsibility/language/foreign politics standpoint?”
On it’s own it mostly that says that you have parents who can afford to send you and that you probably have pretty good Spanish. Responsibility, no, especially if it was through a program. Fair or not, from an adcomm pov, it is just a slightly farther-away special interest summer camp. It only says foreign politics if you make that link in your essay (and if there was some awareness/involvement with it irl of course).
The big job in front of you is showing that you are maturing from a really good student who does really well on tests to a young adult with some ideas of your own as to where you want to go and what you want to do when you get there. So the value of the experience in Spain- or the service trip, or governor’s school, or work experience or whatever else you do, is in what you made of it, how it fits into your larger story. That’s why everybody here can give ideas and suggestions, but none of us can tell you what to do next. There is no single right answer to the story you are writing for yourself 