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?

Hi, I moved on Fri., so just saw your note. You need to take that spindly thing, plant it straight into the ground (no pot) and wait 2-3 years for it to become anything approaching do-able. Don't pinch buds or cut branches, just wait. Get something else, and/or indoor tropicals to work on while you wait.

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.

I haven't had this issue with birch, but am having issues with buckeye right now. There is too much rain and they put on a quick early burst of growth that is too heavy for the stem. I stake them up - they won't need the stake when it gets drier and growth starts to harden.