Here are your parts, includes the wiring diagram.

[COLOR="DarkRed"]2-Unable to locate heater fuse as shown in parts diagram. Where is it?[/COLOR]
The fuse is Item 16 in Section 3. I am not sure where it is but it is probably clipped onto the evaporator coils just follow the defrost heater wiring.
If someone else has worked on this unit they may have removed it as it is no longer available.

I have replaced defrost heater which was visibly burned out, and it is still not functioning in defrost cycle. Defrost timer seems to test OK with 1.5 volt test light, but no power at defrost heater quick connect in freezer compartment when in defrost cycle.

[COLOR="DarkRed"]1-Can the timer be faulty and still show continuity?[/COLOR]
I am not sure what a 1.5 volt trouble lite is.
Also not sure how/where you are testing continuity with the trouble light.
Trouble lights are like the idiot lights on a car they really do not tell you much, a meter is a much better tool for trouble shooting.
That way when measuring for resistance you know what it actually is, the same applies with voltage.

If you do not own a meter, I would suggest you purchase a one. You can get a decent digital multimeter for under $20.00. You do not need fancy though it is nice if the leads are a couple feet long.
If it saves ordering one unnecessary part it has paid for itself and you end up owning a useful tool.
Most places will not let you return electrical parts so if you order it, you own it.
A couple things to watch when measuring ohms and continuity
1. Always remove power from the machine otherwise you could blow your meter.
2. Always disconnect at least one side of any device you are checking. This eliminates the possibility of measuring an alternate/parallel circuit path.
3. When checking for closed contacts and continuity use the lowest scale (Usually 200 ohms). Then try higher scales. This scale is 0 to 200 ohms so if the device you are measuring is 300 ohms this scale would show an open circuit which it is not, you are just measuring outside the scale's dynamic range.
4. When you start always short the meter leads together. This will tell you that the meter is working and if there is any 0 offset.

There is a good STICKY at the start of this forum about it's use.