2) Beeing the author of the longplay I can give you some advices, but in mind that the longplay is from the Russian version, hence colour values from the hearts and max colour each heart gives you are different. Even so, I'll try to give some generic advice.
-You don't need to fill all the hearts at once (unless you are going into a fight), the more hearts are filled, the faster you'll "lose" colour.
-Give preference to bigger hearts. Small hearts are good if you need a boost of a specific colour, fast. You notice in the longplay videos I mostly keep only the big hearts filled (colour capacity above 40), but like I said, colour amounts have changed from the Russian version (as an example, the shell heart allows to store 50 lympha as opposed to the 25 lympha from the German version). Another difference from the Russian version is that we could keep the colour as nerva as long as we wanted (until it technically starts to evaporate) that would prolong your life expectancy, which again can't be done in the German version.
-Regarding gardens. Only revive a tree if you have enough to survive yourself and to fill or almost fill the tree to the maximum. Trees with small amounts of colour are useless. When planting a garden try to plan two cycles ahead, as in, try to have enough colour to only need the garden after two cycles.
-Avoid using gold for any action unless extremely necessary (like brother fights for example), and before you give colour to a sister fill the maximum amount of hearts with gold. That will save you a lot of colour in the long run.
If you need more advice give us specific problems (like the brother you are fighting) and we'll try to help you
Enjoy and good luck
