I have worked as a planner processing variance requests in south Florida.
My advice is to try not to get a variance or variances. It's just an easier path to permitting when you don't have-to. In my jurisdiction, each part of the code from which you sought relief via a variance request was a separate fee. Say the fee is $2,000. You want a variance for a side setback of 10' instead of the required 15', that's $2,000. You want a variance for height of the building, another $2,000. You want a variance for the number of parking spaces the zoning code says you need for your occupancy and size of building, another $2,000. It can get very expensive, quickly. What are you going to do if you petition for three things, but only get one, and it's not the one you really-wanted to make your plan 'work' for you? Avoid the variances if at-all possible. Check with your local building, zoning, and engineering depts about the variances you hope to get and the procedure. The usual thing is that all registered property owners within a certain specified distance from your parcel get a certified mail notice of your variance plans, and you have to go to a planning and zoning board meeting, and then another meeting of the local government body, the city council, or the county if you are in an unincorporated area. It's a long, drawn-out process that could take a half-year or more. Your property will be posted with a legal notice of each meeting, there will be a legal notice published in the local newspaper, and there will be a notice posted at city hall, the village or township, or the county office building.
The first thing you need to do is to make sure that your zoning allows you to do everything you intend to do in the scope of operations at your occupancy. If you cannot for instance operate a motor vehicle repair business there, don't think you can tell them one thing, and do something else. That's a recipe for financial problems when you are issued a citation for operating whatever it is, but you don't have the zoning you need.
We'll assume you have the zoning for all aspects of work you intend to do. One of my friends built a new metal industrial occupancy not far from the Ft. Lauderdale International Airport. He can sell goods, repair motorcycles, and have storage. He also had waterfront property on the Dania Cutoff Canal, which goes to the Intracoastal Waterway, and the ocean. At one point he ran a smelting operation, melting down scrap aluminum motorcycle components into ingots, but he wasn't zoned for that, even though he had an industrial zoning. He had to stop.
It might be more-organized for you to begin another thread. I suggest you find a local architect to help you with the work you propose to do. You're going to need engineered plans for drainage and water retention, a lighting plan, a landscape plan, a signage plan, a parking plan, and a site plan. That's besides the building plans, and they all need to be sealed by a P.E. An architect will be able to guide you through the process. If you were an experienced G.C. you could probably do it yourself, because you would already have the connections, but I suspect you don't. The money you spend on a design professional will result in less mistakes, a smoother path to issuance of your permits, and better oversight of the work. I can get you a referral on the metal building manufacturer my friend used, the building went up with no issues, it's been awhile, and it's holding up well.