1. Not difficult to do at all.....at least on a 727.

2. Yes it pulls straight out but it is tight sometimes. I've re-threaded the speedo cable back on and used the cable nut as a better hand hold to pull. Have a catch pan ready because there should be some trans oil coming out...at least this happens on an auto with fluid in it .

3. I always install it into the outer cover and put it back as a complete assembly. Be sure to put it in the correct position for the speedo gear tooth count!

4. If it's not leaking, no. Can't hurt if you have a new one but I wouldn't replace it if its not leaking.

MikeR