<p>I have a product idea that requires integration into the Microsoft Office suite.</p>

<p>Are there any licensing/limitation issues to be aware of for me to proceed?</p>

Depends...
If your product uses their published APIs and you don't ship any components of theirs "in your box" then you are (probably) just a value added supplier on top of their platform.  You would be telling your customers to have the appropriate MS products in place and then install your App over the top.  That approach is fine and the only reason you need to tell MS is because you will get a lot more business if you are a preferred/certified supplier/partner.  (Depending on which product(s) you are integrating with you should check on MS to make sure that there are no specific license terms around using them).
If you put any of their code in your box then you have to make sure you are operating within the terms of their license and they will almost certainly make you jump through some hoops to get yourself approved by them.  You also have the problem of sharing revenues which is not likely to work in your favour.
In my experience MS don't like doing this with anyone - regardless of size - and certainly not with really small players.
You may be better off approaching them directly before you start and find out if there are incubation projects that you could join to surface your idea.