Definitely retain a lawyer to draft the PSA (purchase and sale agreement) to acquire the property. That document should require the seller to deliver due diligence documents like the current lease, rent roll, security deposit info, past financials (ie 2-3 prior years operating expenses, trailing 12 months, etc) and other property related info. Joel Owens is correct on legal fees for a commercial real estate attorney worth their salt.
Zoning is something you can probably answer before making an offer.
Your purchase price is based on a lot of factors but at a minimum get an educated guess on the projected NOI and then apply the prevailing cap rate for that type of asset and see where you land on price. Even if you occupy part of the space, I presume you will setup a separate entity to own the real estate and then your business entity can pay rent to that entity, so factor that rent into the NOI calculation. As far as cap rates go and market terms for this type of acquisition, a broker would be helpful.
On your debt financing, a community bank may be a good option. Reach out to multiple lenders to get a sense of what terms you can get.