'Best' method to achieve proper clearances is always to 'shim' where possible. This preserves all of the hardening depth at the end of the valve stem. It can be labor intensive and will probably result in having to purchase a few shims (after moving certain others)...but it is the best method...
It is fine to 'tip' the valves provided you don't go TOO FAR (through the hardened portion). This what nearly all machine shops will do. (Combine moving shims and tipping the valves) to achieve proper clearances and maintain the thickest hardening.
Yes, but it will require moving/purchasing shims if any significant amount of material is removed.
IF the head is straight, the valves and valve seats are not burned/pitted then you can LIGHTLY lap the valves, reassemble and be good to go for awhile.
IF the head is shaved, the valve seats...
There aren't that many 'gotcha's' with the 1FZ-FE. They are pretty much a Forklift engine with a fairly refined head on them.
Designed to be serviced/repaired way out in BFE with a minimum of tools.
It might seem daunting (if your first time to go that far on an engine) but if you follow the...
These days....unless you invest in something like a Ron Davis radiator.....then I consider that vast majority to be 'disposable' after 6-10 years depending upon construction.
Longevity aside....you DO want something that performs well. The best performing radiators currently available have...