You have picked some difficult ones to start out with! Most juices I make use about 10% flavoring, by volume. Other than the ones you list, it almost makes no difference what the flavor is. 10% is a good starting point, and often what I stay at. The ones you list, other than perhaps chocolate, are quite different than this. Tobacco can be made from Tobacco Absolute, a very thick and hard to work with material, often dissolved in alcohol to use as an actual flavoring. RY4 is a caramel based tobacco, so get the tobacco juice how you like it first, then add some caramel to that. There are MANY tobacco flavorings out there, from cuban cigar to winstons to pipe tobacco.
Easy tobacco flavoring and quite good:
http://www.e-cigarette-forum.com/forum/liquid-extraction-tobacco/99774-vg-pipe-tobacco-essense.html
It should work with any loose tobacco you can get. I did it with a fruity pipe tobacco.
Menthol is a crystalline substance and is generally dissolved in alcohol before using as a flavoring. It will take experimentation until you get it how you want. Search menthol in this forum for more tips.
Coffee is another very hard one. PA coffees are generally very very strong (use maybe 1%) and very dark in flavor. I've tried several, and none really do it for me, but I've only begun trying coffees. Lorann's coffees are ok at best, to me, with Keoke Coffee being maybe the best, but still not good to me. Capella Cappuccino is excellent, but you might not be able to get it in Bolivia.
I suggest trying some other flavors first, just so you learn how to mix juices. With PA, unless it says "very strong", you can probably do a 10% flavor and get a pretty good vape. Of course not all flavors are going to be what you expect or actually want! For instance, I have yet to find a good coconut flavoring, or a good cherry. PA pear is one of my favorites, and mixed with a touch of Lorann Bavarian Cream (another really good one), its heaven.
Make some simple juices first, then you can vape to your heart's content while you research more details of these other more advanced flavors. Nothing is stopping you from jumping right in, but these are just my opinions.
