Oh yeah, this would take long to make, trust me ;-) I've done smaller projects revolving around D3 calculators and the devil is in the detail. There's lots of hidden mechanics and caveats to look out for, so this is not something you can do over a weekend.
There are lots of websites that offer those numbers though:
As Bagstone posted, I have a spreadsheet that calculates dps and EHP very accurately. The main limitations are that it is primarily based on a single skill and a single element, and for wizards. It doesn't calculate effective dps based on actual skills or combinations of skills, nor does it compute total CD reduction. It also doesn't compute cost reduction because the actual calculation for channeled skills is not completely accurately known. There is a spreadsheet floating around the official forums somewhere in the wizard section that does attempt to calculate some of those things, though I haven't spent any time with it myself. It was written by dolynick and so far seems pretty good.
Thanks for the link. I never bookmarked it for some reason and it keeps falling back a few pages so I never remember to look for it. My thoughts were to use it with mine since it seems to compliment mine fairly well, though there is likely some overlap.
When wasn't channeling cost Attack speed * Resource cost? Unless you're referring to trying to calculate effective dps based on the uptime possible, which should still be the same as anything else. It's difficult to get a read on it due to how the ticks roll up into displayed numbers, but I'm fairly certain you can expect it to behave the same.
That's because there are way too many variables to calculate "damage per minute" accurately:
How many monsters are around you and in which range?
How many players are in your party?
What skills and passives, especially group support skills, are your party members using?
Which items are your group members using that might impact the group's DPS (Sever?)
What kind of monsters are you fighting: A Tremor in defense stance with lots of damage reduction? Elites with CC abilities that limit your effective DPS? A group of illusionist mobs that burst your DPS for a short amount of time? Just white mobs?
There are literally millions of synergies that you'd have to account for. All that people do right now is run Ghom tests - it's one single mob versus one single player, and still serves as basis for discussion as to how valid this result is. Imagine you had a DPS meter like in WoW, you'd do one complete rift, and you'd look at the DPS curve. It would be like a very spiky graph plot. Which segment of this graph would you call your average DPS? Just the average over time? What does it show you? It's exactly what people already calculate - average rift clear time. A Conduit Pylon ruins your entire results, though.
Don't get me wrong, I'd be more than happy if such a tool exists. If you wanna go for it, absolutely by all means go ahead. But as someone who only took small segments of this "simple overall tool" I can tell you that even implementing 1% of the functionality you want can take forever, and not just talking about interface here (of course, a good interface takes lots of time and testing). I just want to give you an honest heads-up that you are drastically underestimating the complexity of your project.
You can easily calculate max/min crits for skills using weapon damage and dps calculations.
Damage per minute = DPS * 60 seconds per minute, but not sure why you want that as opposed to just using DPS.
Burst damage is more complicated and involves a time frame, skill selection/combination, and some other factors.
Actual skill dps = char sheet dps * skill weapon damage for skills that you can spam, such as channeled skills. For skills you only use so many times the damage is more like: skill damage * DPS / APS * average casts per second
In short, the information is out there but some of the calculations are just complex and/or just too variable to be of much use. You might have 1 dps against singles but likely a different dps against 2 mobs, and different still against 3 with a non-linear scaling.