The wash and cure is very important. The wash part removes the resin, which should not contact the skin. The curing is important, too, as the resin is only partially cured by the lamps which create the part.

For the slicer, there's quite a few videos providing instruction for use. You've indicated small parts, which means that hollowing isn't too important. Larger items (greater than 10 mm across in at least three directions) should have drain holes. If they don't, the inside resin remains in liquid form and will eventually "age cure" and expand and crack the part, creating its own drain system!

Will your parts be mostly considered an engineering type of design? Straight lines, uniform structures such as cylinders, spheres, rectangular prisms, holes, etc? Organic designs are those that can't be pigeon-holed into such a description. You'll see those in modeled characters from video games, animated videos, creative artist types making creatures from imagination.

If your parts are the former, look for engineering directed software. The bare basic version of such a program is TinkerCAD, free, web based and easy enough to use, plus the usual video tutorials on YouTube. As you become more skilled, you may discover you require more sophisticated design software. Fusion 360 is a pretty powerful program, and can be challenging to learn, but the YouTube videos abound.

If you're a coding type (programming), another free program is OpenSCAD, text based 3D modeling software that makes for very easy parametric model creation. I'm no wizard when it comes to coding, but I really enjoy OpenSCAD for precise model construction. If properly written, the code makes quick modifications for resizing and similar adjustment.

Of course, you've already found a good resource here. Post a question if you run into a bind.

There are quite a few sub-reddits of value as well for help and information.