Do you think the iPad would be even more successful if the mini had launched first?

No, I think the full size ipad offers a better experience on the web and with with video. The mini offers a better gaming experience though, thats one thing I think the iPad is too big for, the mini is Wii U-esque. reading ebooks im not so sure about. I think also part of the iPads success is its ability to to an alternative to 10" netbooks and if a smaller screen size was offered it initially may never have taken off in the same way.