i think you can use the branches ok, especially if you leave em in the sun for a month, but they dont break down very quickly. Best wood is old and rotten - so, light.
bobcat wud be ideal, and the width of the
bucket is prob just right for width you can lean into from both sides, once it is a garden !
'
Where are your roof drains? can you put the beds where the roof drains will
feed the buried beds? can you just build a trench filled with rocks to get it there? (french drain)
Go look out in your
yard, does it all drain in one direction? all fall away from the house? this should tell you where to put the beds, and some of the clay that comes out of the garden hole should be spread as swales/berms to direct water to the areas you want it, and charge up the buried wood over the winter. remember to put the tallest stuff you want to plant furthest back, and with a
swale to channel water to that fruit tree too.
you can use a garden hose attachment for injecting water and nutrients to tree
roots, to dig in rocky clay if you dont mind the mess ! look for "deep watering" and tree
root injectors.
coul prob start digging those drains with it now, and then you have a place to put all the rocks you find as you are doing your other projects.
dig a fruit tree hole with the attachment, then once it dries out, loosen the edges and bottom with a spading fork, to break up the clay so the roots can expand. otherwise they will just swirl around and rootbind.
as you place mulch around it, the earthworms and humus will loosen the soil, and you can plant it next year without having to dig it much (still use the fork, push it down and wiggle /lift it just till the soil breaks/ loosens, and the mulch will work its way down there,.