The only way you can use the iPad as a hotspot for your phone is to jail break it and then purchase a tweak from Cydia (the jail breaker's "app store"). The iPad never got the ability to hotspot from the carriers, so that's the only way to do it, unlimited data or not.
The IPad Forum is a community of members from all walks of life and from all over the world coming together to share our experiences and to help each other learn about this wonderful piece of technology the Ipad. There is a wealth of information already here in the many threads we have so doing some searches will answer most of the questions you have. If then you cannot find the answer you are seeking then by all means post your question. There are many friendly and informed members here only too willing to help you.