Unsalted margarine is another story. Never melt solid shortening for a cake. Allow to warm to room temperature unless using a liquid shortening. Liquid and solid shortening have different recipes and do not interchange. One half cup of applesauce and 1 tablespoon of Canola oil can replace one half cup of solid shortening in many recipes.
Flavoring are varied but real flavoring is preferred over artificial in any recepe.
There are also cherry, pistachio, rose, raspberry, coffee, rum, etc. If a cake has any fruit, the flavoring should be lemon or orange. Grated orange or lemon peel can enhance the liquid flavoring. If the cake contains nuts, the best flavoring is vanilla, orange or almond. For a plain cake, any flavoring can be used.