Why not? Well, you can do it, but you may or may not want to. Carving is more traditionally used on conifers (pine, larch, fir), so if that matters to you (being traditional about bonsai) then you may not choose to do it, but others have and if they do a good job it doesn't look terrible at all, though possibly a little strange. However, why not just cut the unwanted parts off flush with the trunk (or branches) with a concave cutter? Why not Google 'bonsai' with 'jin' and 'shari' (the terms for carving) and learn more about them?

I sure hope you haven't given up on your birches yet! Many birches and aspens are susceptible to borers, which may be causing the trunk damage you describe. Unlike some other gardeners, I'm not inclined to dispose of a tree because it has borers, and thanks to my local (northern colorado)extension office and expertise, have had tremendous success using beneficial nematodes to control borers. I live in Zone 5, Colorado, and applied them to my trees in liquid form when there was a severe infestation of borers three years ago. Beneficial nematodes are not harmful to the environment or humans and are being increasingly used to control pests like borers very effectively. Three years ago, the treatment also saved three of my mature aspens (10" diameter trunks). I'm not predisposed to cutting down a tree at the first sign of borer now that I've had such great success. They're inexpensive, effective, easy to apply. What more could a gardener ask for? Beneficial nematodes can be easily obtained from a number of manufacturers and are live microscopic creatures that are naturally predatory parasites to borers. Borer infestations are easily controlled using beneficial nematodes in one season in my experience. They are sensitive to freezing (but you can refrigerate until you can use them),high temps, and ultraviolet light, so should be applied by early summer at dawn or dusk to trunks and roots, and watered in well (or later at higher altitudes). One can buy them cheaply and apply them in liquid spray form with a standard yard hand sprayer. I happen to even have used my Miracle Gro sprayer. I swear by these lovely (microscopic) creatures, as they saved my beautiful trees! I don't know about the rest of folks, but as a gardener I'm more inclined to save try to my trees than destroy them whenever possible, and particularly in this economy, to preserve the value of my property that mature trees bring--not to mention the value and pleasure they bring to me in their beauty. Below is a link you might find helpful and/or you might try your local ag/extension office. Good luck! Here is a link that might be useful: Beneficial nematodes

Thats a tough one. Never had to water such sized fresh planted trees. I guess it depends on soil type and current state of your soil from a moisture point of view. Oh and if the plants were containerised or rootballed from a field. I would water a good large amount at reasonable intervals without over watering more than little but often like some people do which often leads to dry areas due to poor water penetration. Then ofcourse you will have to judge on how the spring and summer goes- good luck- I am sure the trees will give you some indications as to if they are happy or not.

Love celery girl's ideas, but I don't think you should paint the brick. Here's a combo that has a bit of the greenish-gray you don't like. Instead of hating on it, use the same shade for your trim and garage. Then create a front garden instead of your lawn,. Notice below how the rounded, deeply planted bed minimizes the wide brick wall. You could do the same on your house, leaving the tree on the left and adding a new, deep garden bed. This is best planned with the help of a designer from a small garden center using native plants. For any future red-brick-house buying, reddish brown roofs or roofs the color of the grout go best with them with trim paint also the color of the grout. Your grout is light tan, so a tannish brown roof might've been more harmonious like the one above. Still, the one below in gray slightly greenish tint looks good, too.