To answer your first question - yes, whether they were real or fake, you would probably wrap the stems anyway! I'm having hessian and lace. If you go for artificial, I wouldn't worry about covering the bottom of them - no-one is going to be looking that closely!
Colours - there are some great artificial flowers out there - I've seen great reviews about country baskets! I'm on a DIY brides group on Facebook, and loads of them have made artificial bouquets, and you really can't tell, they look great!
Smell - they obviously won't have that real flower smell, whatever you do to them. How important that is is up to you.
I love real flowers, so I am having real for bouquets but have used artificial to make decorations - I'm going to look into getting my bouquet dried or preserved in some way, so I can enjoy it for years to come. Of course, with artificial flowers you don't need to worry about that - they will always be a lasting momento.
I would get some artificial flowers and make a bouquet, then see how you feel about it. If you like it, great, if not, order real for the day and use the flowers you have in your decor, or just in a vase at home.
Hope this helps! X