Renting/Leasing farmland shop zoned Multi use Ag in Oregon

[Troy Mcdonald]

Hello, i'm in the middle of negotiating a lease for a 4200 sq ft building in Central OR and am looking for some clarification if possible. I own a Hot Rod and Performance shop outside Sisters OR currently. My building is being sold and owner retiring. I've located a building in Tumalo OR that is property class 541 -- FARM for assessment purpose. It is zoned MUA10 multiple use Ag 10 acre, LM landscape maintenance combining zone and SMIA surface mining impact area. The terms we're close to agreeing on are favorable but after looking through the zoning laws and searching the internet i'm not sure if i can legally rent it and run my shop there. It also has an assessors warning attached that says it's (Farm-unzoned potential additional tax 308A.068. Can anyone tell me if i can rent this building legally or not? In the zoning laws under conditional uses permitted there is a section i believe i fall under. Does that mean she/I would need to obtain a permit from the county for it? There expensive and i'm not sure the owner would want to obtain one. Also she has mentioned some other things she is thinking about doing with the property and they don't fall under uses permitted outright either. When i meet with her i want to be able to clarify any potential problems or risks for her or i  if i rent it or not so she at least knows what has to be done before she ends up in trouble or i do. 

Any help is appreciated, 

Thank you.