The standard option for a shop floor is a concrete slab. You’re probably not going to go to the trouble of creating a basement beneath your shop, although it is possible. The weight of most woodworking machines suggests that a concrete floor is the most solid and durable substrate available. It has the potential to be used as thermal mass to store heat from your heating system or from the sun, but it can be tiring and hard on your body to be standing on concrete all the time. You can add a vapour barrier, 2x4 sleepers and a wooden floor above the concrete to ease the tendency of the floor to strain your feet and back, or you can add anti-fatigue mats in key areas where you’ll be standing for longer periods.
Use whatever image hosting service you like and post the link to /r/woodworking. The key here is it needs to be apparent that you've built the entry, and you follow the photo requirements listed in the contest rules. Submissions of finished photos only will not be accepted for entry. <-- I can't emphasize this enough, you absolutely need more than 2-3 photos for a valid submission. I will no longer accept entries that have albums that go from rough stock to 90% complete in one jump.
Let’s be clear about one thing: No workshop is perfect for everyone. If there were, I could simply give you a precise plan to follow with clear dimensions. Every person who comes to the hobby, avocation, or profession of woodworking has his own particular collection of tools and his own peculiar work style, skills, and desires for the kind of woodworking he wants to do that gives him a unique approach as to how he will lay out a shop: where the tools should go, where lumber and supplies are stored, and how much bench area he needs.