Where to start is always the tough part because it is really just a lot of guessing until the first few cuts open wrapper. The sawyer will likely have a good handle on doing it some particular way and most of them are engaged in turning trees into square edged things, not rounded stocks...
Limbing it to uncover the trunk will make a lot of things obvious...
As to sap... The extremely common wood used for all sorts of furniture here in the US right now, prima vera, is a great example of the sap problem. The trees are incredibly huge... so huge they time falling to avoid full moons... The sap actually has tidal effect! Falling it will thousands of extra pounds of water can damage the wood more.
Trees in the realm of your walnut are not there for concerns because they are both much smaller and far stronger, more elastic wood.
Some claim there is a difference in drying, but the edge there goes completely to added water... Wood will start having potential problems the minute the water starts leaving cut surfaces. Kiln drying is not really about getting water out faster, but rather about controling the water evaporation rate so the wood is not damaged in the process. Kiln-drying NEVER improves wood over proper air-drying. It only does it faster with "acceptable" levels of degrade.
Start with the easy, obvious pieces. The butt log should be at least 6' from cut to root bottom. After that the sawyers rig determines how long each log above should be.
Making a log cut just above the exposed iron is probably the safest way to dig it out. The iron in the tree is most likely above the hanging section... Metal detectors are a very good idea, but not infallible.
Gimme cuts:
From the fifth picture; Forks up in the tree (relatively vertical sections ONLY) should be split to produce two "Y" shaped pieces. That will expose potential crotch figure, which will be there, the question is how much... It also is a good place to look for quartersawn curl out away from the crotch. Marbling is generally limited to the lower portions, so any you see here is a great sign. Slabbing the halves from the exposed faces out is better than a quick and dirty "through and through" slabbing of the entire piece because it will do a far better job of following the pith. Grain run-out is not a good thing in blanks and making cuts from the outside of the log which are parallel to the pith is much more difficult...
Have to run, will try to add more later today...
art
Oh, if I did not live in AK I would probably be jealous!
