Is dual suspension actually inefficient, or is that just a hunch I have? Is it worth getting a bigger bike because I am bigger? How much of a difference does that make? What type of bike should I be looking at for my needs? Hybrid? Are there other kinds of brake systems, other than vbrake and disc? What kind of tire suits what I need? What about storage options for my books/groceries?

I have much more than one vague question,