My vote is with the guide rod mount/caster ball joints. I went through the whole front end and one of the symtoms you are having was eliminated by replacing the guide rod mount. Fast lane sell a kit for around $80, I did not have to compress the spring out either. Once you go under the car, hopefully it will be very clear to notice since in most cases the boot is torn and rusted ball joints with dried up grease are very visable.
The second sound you are explaining the "thunk" is usually front sway bar bushings as Brian has explained in above post.
Good luck and keep us posted

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87 420 SEL
Looking for a nice mid 80's MB diesel.
87 BMW 528e (Sold)
99 TOYOTA 4Runner
1989 Honda Accord (Sold)
1988 Honda Accord (Total)