Call me old fashion, but I am a firm believer of do on thing and to it well. Your list of requests have a very broad scope and it wasn't clear if you expected one software package to do all of it. There are many great open source software packages for use with business.
GnuCash is an excellent accounting system to help you keep your financial accounts organized. I'm not really sure what is entailed with 'issuing a W-2' other than handing your employee a form. I have seen various companies use a combination wiki, dms and cms, all of which have many open source choices, to organize corporate data, and serve it in an clean and clear fashion to interested parties.
As far as tax filing software, it looks like this is not a foreign question to slashdot:
http://ask.slashdot.org/article.pl?sid=05/03/09/011259
One of the products offered in the above link is:
http://opentaxsolver.sourceforge.net/ Open Tax Solver
I am unclear what you mean by legal template. If you mean pre-formated document, OpenOffice.org has a large collection of templates you can browse through. If you mean canned agreements and contracts, they are around on the web, if you search for them. I must add IANAL so be careful using any generalized contract.