For reference check out: http://www.quora.com/How-did-Dropbox-reach-its-first-100-100... and: http://vimeo.com/16091659 Drew is very inspiring.
I'm currently looking at a 6 week cycle for one "iteration".
It will depend on how difficult your product is, as well. There was a linked article on HN recently about how dropbox's MVP was too complex to build ahead of time, so they used a video demo as their MVP.
1) using as many frameworks/themes/pre-made stuff as possible to eliminate subjective decision making on your end 2) reducing options for your end users as much as possible. Stuff like items per page or random other minute extras just don't matter. Just make the decisions for your users. 3) The most simple version of your idea that is still unique and useful
Its subjective. Being an entrepreneur you need to figure out what the smallest unit of measurement is to validate an idea. So based on your expertise, you should sort of know what that is. Example: design ? well its based on your audience. If you are launching a tech oriented product.. you could probably get away with a not so nice design. If its something to do with money, you probably need to use a design that builds trust so you remove that as a factor from validating your idea.
From all the high profile pivots you read about here, I don't think anyone really has any idea, sometimes it works sometimes it doesn't. For business solutions its a little easier IMO, because you can talk to customers, solutions and problems. For consumer oriented products its much harder.
For minimum viable, you want to get to 'Adequate' on the core components. That's probably the main product you sell and whatever payment / lead capture is going to be critical for you (email signup, payment processing, or whatever).
A good final, last question to ask is if launching now the way you'd like to has a realistic danger of permanently screwing up your brand. If not, definitely go for it as long as the product is Adequate and the lead/payment systems are Adequate.
If you can get to Excellent very quickly without much more effort in an area, maybe go for it. Take measures to ensure your brand isn't permanently damaged by being too lax somewhere, and then get it out there.