1)Are full-time offers more competitive than internships at MBB and tier 2 firms.
Hmm, honestly it depends on how you define this. It also depends on the channels in which you are recruiting as well as the time period (year), competition (other candidates), geography, etc. Quite honestly it's not really worth thinking about - getting either offer is incredibly tough and you need to be at your best!
2)In general, how would you compare the difficulty of entering into a tier 2 firm compared to an MBB firm on a scale of 10.
Pointless exercise. They are both tough. Furthermore, there's an element of “luck of the draw”. I know people who aced MBB and didn't get tier 2, and vice-versa. It depends on match, culture, performance the day of etc. Let's say 10 and 8, but you're worrying about the wrong things here.
3) If you have an opportunity to co-found a student organization(not related consulting) and an opportunity to do an internship at an F500 company which is better if you aim for MBB in the future.
100% the 2nd (internship at F500). This probably applies for almost any other future job you want to get.
4) Do tier 2 firms also look for a very strong GPA and strong brand names.
5) Can anyone give me feedback on my CV
I always offer my 1-minute pass over for free. You'll get my first 3-5 observations of your resume. Of course, the full review (to get your resume to 10/10, at a level where recruiters have told my candidates “this is the best CV I've ever seen”) does require a full session.