Workbenches have flat tops, though sometimes at the rear there is a cavity called a tool well that contains tools and components (and prevents them from falling off). One advantage of having the well set into the top of the bench is that, even with a variety of objects in the well, a large sheet of material can still be laid flat over the entire surface of the bench; the contents of the tool well offer no interference.
Whether you’re setting up a new shop or upgrading your old one, a good, sturdy workbench will almost surely be central to your plans. We can help. Our editors and contributors have produced more than two dozen articles and videos about benches and assembly tables. We’ve included everything from a simple but workable plywood bench to a classic hardwood bench complete with vises. You’ll also find full project plans, as well as tips for installing vises, making your bench portable, adding storage, and more. Some of our workbench plans are free, and the rest can be purchased in our store (check the links below).
Regardless of which type of screw you use, you'll need to flip the panel and use a countersink drill to on all of the exit holes. Drilling MDF leaves bumps, the countersink bit will remove them, and will create a little bit of space for material drawn up by the screw from the second sheet of MDF. You want to remove anything that might keep the two panels from mating up flat. I set a block plane to a very shallow bite and ran it over what was left of the bumps and over the edges. The edges of MDF can be bulged by by sawing or just by handling, and you want to knock that down.
I would say take the shed, you'll find some use for it. I have contemplated this question also. I have a 20' x 11' basement shop, thats quickly loosing space. If you live in an area with a harsh winters (say the Midwest), does it make sense to heat the shop through the week if you are only working in the shop on the weekends? Or do you run the heaters just when you are working in the shop? What kind of heaters are recommended (radient, wood stove, etc.)?

Windsor Design is an interesting brand in that it is not actually its own company. Instead, Windsor Design is one of the in-house brands sold by Harbor Freight. While it may be a store brand, that should not dissuade you at all as Harbor Freight is known for selling some of the best products available for all fields of construction. Granted, this may not strictly be the best table available, but it does provide a solid mix of features to make it a good value.
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In class, each student will build a detailed hall table that is complete with mortise and tenon joinery, biscuit, dowel, and floating joint construction.  The student project is presented with a variety of design options and formats as to meet the experience and comfort level of each student.  Depending on their experience and comfort level, students are encouraged to make a simplified version of the hall table or tackle a more sophisticated and complicated version of the same project. Your only limitation is the amount of material you receive in your lumber pack (~24 board feet).
I agree that even at 12x12, things'll be "cozy" inside. That's OK. Keep in mind that this will be a general purpose hobby shed, not just a wood working shed. Even 12x8 would be plenty big enough for building 1 meter wingspan bungee launched RC gliders. And for the electronics projects I do, I only need enough workbench space to do some soldering with a 3rd hand (for electric guitar pedals). If I need more room than the shed offers for wood working projects, I'll just roll the table saw down a ramp and do my cutting outside in the sun.

Anyway, I'd like to know if I'll be able to keep (EDIT: and use) all my tools out there (current and planned) without having the shed become a rust-bucket for the tools and machinery inside. I'll have a 10" contractor's saw out there along with a drill press, a sanding belt, a router & router table, and lots and lots of old tools that I inherited from my Granddad years ago. I live in the Seattle area, so it rains A LOT. But I'm hoping that with the proper ventilation I can keep the tools in the shed dry.

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