such a cute cookie! you have nice piping skills!
i outline with a no.2 tube. the trick to outlining with glace is to make sure it is stiff enough not
to go "flat" after you pipe it. toba's recipe is 6-8 HEAPING tablespoons per half cup and i use this as my baseline, but i really judge when it is ready by eye. it needs to be holding it's shape for about 10 seconds when dropped from a spoon. the icing itself will also be just starting
to look like pulled taffy as the paddle goes around. if you go beyond the this point, it will get too darn stiff and your hands will hurt from all the sqeezing you have to do to get it out of the tube. you can always do a more accurate test by pushing some icing thru a tube with your finger before filling your bag.
for the type of cookie you photographed, you should let the pink outline dry before flooding with the white (when i outline a cookie and i don't want the outline to show, i do it while the outline is still wet). i would give your outline 10-30 minutes of drying time before flooding. drying will help your outline maintain its shape since glace is not as mannerly as royal icing
for your flood, i would recommend using more of it. you can really put a lot more in without worring it will go over the outline.
the white coloring will help you white look more vibrant. just add a little though. the whitening can cause some textural problems with the icing if too much is used. using milk instead of water in the glace will help too.
the white stuff can also cause the glace to have more of a matte finish so it's a balancing act when using it with glace. i am trying americolor's white this week to see if it behaves better than the wilton stuff (which is what my comments are based on).
i made easter cookies yesterday and used RI accents and it just reminded me all over again why i love glace and am not fond of RI, lol.