Questions regarding general data structure/algorithm knowledge and finding jobs after graduation

Sorry for the broad title. I'm a senior in college, and I only have had one internship. I've also only been programming for a year and still don't know how to exactly implement depth first search (just an example) on a graph in code. However, I can understand the concept and write pseudocode for it. In addition, I'm more interested in starting a startup right now than studying data structures/algorithms. I have my whole life to learn that stuff, but only while I'm in college to be surrounded by motivated peers that will aid me in my startup endeavors. So, my questions are as follows:

1) Is it more sufficient to know the concept of different data structures and algorithms and be able to write pseudocode/general code for interviews? For example, graphs are implemented in so many ways (matrixes, adjacency lists, nodes) and knowing dfs and bfs on only one type of these graphs would be constricting. Knowing the general code and concept I think would be more important for interviews, no?

2) Is it harder getting top-paying jobs at microsoft/apple/facebook post-graduation after I get a job somewhere else, study for the top-job, then apply?

Thanks for your help.