Some quick info on the programs and approaches. Feel free to ask more in-depth questions whenever you need more clarification.
Illustrator is vector-based, which means your document size can be literally anything at any point in the creation process, and it won't matter. Vector is not made of pixels, but mathematical directional data. This is why Illustrator files have no resolution. It will always scale.
Photoshop is raster-based, which means your document does not scale. If you draw a single dot and try to make it 200% larger, your dot will look fuzzy as the program tries to approximate what you're doing. This means if you paint your image at 1x1" at 300dpi (dots per inch), it will look absolutely terrible if you tried to make it 3x3". There was still only 300 dots of data that you are now trying to make occupy 900 dots.
Vector-based artwork looks very graphic-designery, with clean, smooth lines and blocks of clearly defined color. Very "modern"
Raster-based artwork looks painterly, and is the closest approximation to real-life drawing/painting. Photographs and scans of artwork, anything in the real world brought into the digital, are always portrayed as raster-based artwork.
Don't force yourself to go digital! Certainly try it, as it is infinitely more forgiving, but there are many things that digital can't do, like the subtle gradations and transitions of watercolor paintings as the ink spreads across damp paper. Brush strokes of oil paint are also a little harder to duplicate, but those can be imitated.
Experiment, but know that digital is not the end-all (and this is coming from a digital painter). And have fun! That's what experimenting is all about!