How to convert minutes to hours/minutes and add various time values together using jQuery?

There are a couple parts to this question. I am not opposed to using a jQuery plugin if anyone knows of one that will accomplish what I want done.

Q1 – How do I convert minutes into hours and vise versa? For example how would I convert 90 minutes into 1 hour and 30 minutes. In the code below how would I get “totalMin” converted and displayed in “convertedHour” and “convertedMin”?

HTML:

<span class="totalMin">90</span> Minutes

<span class="convertedHour">0</span> Hours
<span class="convertedMin">0</span> Minutes

jsFiddle: http://jsfiddle.net/ExFBD

Q2 – How would I add up a group of time slots? For example, How would I add 1 hour 30 mins, 2 hours 45 mins and 2 hour 15 mins together?

HTML:

<span class="hour-1 hour">1</span> hour
<span class="min-1 min">30</span> min

<span class="hour-2 hour">2</span> hour
<span class="min-2 min">45</span> min

<span class="hour-3 hour">2</span> hour
<span class="min-3 min">15</span> min


<span class="totalHour">0</span> hour
<span class="totalMin">0</span> min

jsFiddle: http://jsfiddle.net/DX9YA/

Q3 – How would I take a time value (3 hours and 30 mins) and add it to a real time stamp such as 10:30 AM? How would I take AM vs PM into account?