The only reason you will sand the base is to remove dirt and nibs.. Base can not be sanded before top coating... There is a chemical adhesion with base and sanding it screws that up.
You are going to need test panels with your candy applications too... and you will also want ot over reduce the candy... this is not a 2 or 3 coat job either... if you can get it in 8 or 9 coats over reduced it will come out much nicer and less issues as far as stripping and blotching etc....
Covering a car in filler can be done by hand and 2 part glaze such as "Icing", but if you are going to do so, get a polyester primer.. it is the same thing only sprayable.. 2 or 3 coats should be enough to level out wavy panels...
and yes it will hold up to driving... It is not intended for smooth base, but to get the panels straight... Flat paint jobs come from flat panels, and that comes from many hours of sanding primers,fillers, and clear...
Here is a candy thread with 74 replys..
Candy Paint Info
Here is 1 thread on polyester primer..
Poly Primer
Just go to the search button after you are in the body/exterior section and type in these type words and you will find hours and hours of reading info...
Also read Martinsr Basics of Basics