24x7 support and how to charge?

If you mean the conversion rate is the same (meaning you're making a lot more revenue with the larger price), then that's the right call. If you mean that your net profit is the same but you have higher unit sales on the first price I would go for the lower price to have more customers (and more chances to have them buy an IAP eventually, or leave a good review).

Are you the manufacturer or reseller? If you are the reseller, typically about 40-50% above cost. Use the MSRP as an indicator.

As someone who has worked in pricing for almost 30 years, I know that one of the biggest myths of pricing is that you should only offer one pricing model. Offer two - both subscription & transactional. Customers will self-select &/or the market will segment, and you will quickly find out what is their preferred pricing model. As an aside, another pricing myth is that you can low-ball your pricing and raise prices later. Its successful in ~10% of attempts. By default, the choice of pricing models also states the obvious. Its not about what you want. Its about what the customer wants. And yes, you should have three choices. One choice gives you a 50:50 chance of closing the sale. Two choices forces the customer to make a price-based decision. Three choices, and the customer says "which one do I buy?" not "do I buy from this outfit?" and secondly they are forced to make a value-based decision. Also think about creating a decoy product, and on the pricing page on your website, lay the packages out dearest on the left, cheapest on the right. Happy to chat further about any of the above...or more!

What you are asking for has one simple answer: Marketing. I assume however that you would want a more specific how to guide for such marketing efforts. I won't venture in giving you a ton of possible irrelevant examples but I would like start our conversation by saying that if there is no market demand and you do have a clever useful product you need to market the emotional need and consider why it hasn't been served. When you find that this is what you leverage.

For me personally, no. However, what you really need is a larger data set. Gumroad just did a post on prices ending in "9": http://blog.gumroad.com/post/64417917582/a-penny-saved-psychological-pricing 37signals started with prices that ended in 9: http://37signals.com/svn/posts/1287-ask-37signals-how-did-you-come-up-with-pricing-for-your-products ... but they later did research and found it didn't matter (for them). The answer for YOU will likely be to test these things for yourself on your SaaS app.