Is it possible to increase the number of downloads by major updates or is it better to release a major update as a totally new app?
Apps can definitely be revived with an update. It doesn't even have to be major. Just take a look at the last few months of Tap Studio 3 rankings in AppAnnie or somewhere. We released an update with iPhone 5 support (finally!) and we have really reversed our slow slide.
Does anyone else think "Minor bugfixes" updates are like saying 'bump' in a forum? We're planning on keeping and building momentum with a stream of 'new content' updates. We'll release a simple, fun game, and from that and the feedback we get we'll build upon. First buyers will see the game grow and will have reasons to come back every update; new buyers will find more bang for their buck as updates come. We as costumers value this approach the most.