Ask HN: All about having/finding partner/cofounder

First, little background about myself. I have been listening to HN community for some time now. I've come to love this community, it's spirit, contribution and great advice from entrepreneurs of all levels. Having 7-8 years of developing mostly enterprise web applications, I have realized that I should combine my drive, my proactive nature with my recent passion to create something of value. I should take risk, work for myself. Greater the risks, greater the rewards (I'm not leaving my day job any sooner, yet). I have a few ideas (I'm constantly thinking about new ones). I'm going to pick one (which I think has great potential in terms of creating value and viable business) and implement it. But I don't have any partner, yet. I have found a few like-minded people, mostly at work. They share my dream about being an entrepreneur and have shown some interest in partnering with me.

So my questions to you is all about having/finding partners/co-founders -

1) Why? - Everyone from Richard White in Entrepreneur's manual to many HN members strongly advice on getting a partner. Why is it so important to have a partner in your opinion? Can we do without having to have a partner at all?

2) Who? - Whom do you prefer to choose as a partner? What traits/characteristics/unique value propositions do you look in prospective partners? Should they be close friends or complete strangers would do? Do they have to bring something unique value to the table or it's ok if they are not much different than you? How do you know a person is a right partner ("your partner shares the same dream as you and likes you idea" is implicit here). In general, all advice about 'finding a right partner' is welcome.

3) How to decide terms of partnership? - How do you decide to split profits (if any, ever) between partners? How to decide the percentage of partnership? Does have to be equally split always? Of course not, but then what is the basis of deciding the percentage? Why would my partner be ready to accept anything less than 50%?

4) Can you please share you personal story about finding partners? I know there is no silver bullet. Each story is unique and cannot be applied to other situation as it is. But I always find personal stories inspirational and insightful, if I keep my eyes open.

Sorry for such a long question. And it demands even longer answers. I know you guys are all very busy. But I guess many budding entrepreneurs may have these questions. I'm hoping, in the good spirit of our HN community, all you experts would shade some light on these questions.

Thanks a lot in advance for your feedback and advice.