assumable loans?

I have recently found an intriguing commercial deal with 75%-80% of the purchase price being an assumable commercail mortgage in a mutli-million dollar deal. Question 1: What is generally required to assume a mortgage of around $4M? Is it based mainly on the project’s numbers or on personal guarantees?

Question 2: Where might I find an equity partner to help me with the down payment allowing no payment for 2 years with balloon and relatively high rate of return…say 10-11% per year, so I can get the project numbers up since it is currently mismanaged to do a refi or resale of the property?