Ok here goes.
To undo the lower balljoint:
1. Undo the ball joint retaining nut about 10mm or so. If it's just spinning I tend to Jam a 22mm spanner (or whatever size fits) between the balljoint and lower arm and lean on it to prevent the spinning, prity much like a balljoint separator tool.
2. As you are replacing the Balljoint you only need one piece of wood, the second would be to protect the ball joint rubber boot if you were reusing it. The wood is to protect Fifis underside from the great big bar you are going to use. You need to slide the big bar behind the balljoint (mind the cv boot and get a thinner bar if you need to) and put one end up against Fifis underside (with the block of wood in between) making the biggest triangle you can. One end will be sticking out diagonally from the wheel arch and the other will be jammed up against Fifis underside. I've drawn you a picture as this is a little hard to explain. You need at least 1 meter sticking out and the bar needs to be as inflexible as possible. I've never done one on a C5 so do look at if any rubber will be damaged by the bar when the arm drops 20mm and protect it with wooden blocks if it will.
3. It helps to have an assistant for this bit but is perfectly doable alone. You or your assistant need to stand on the end of the bar and gently oscillate it. No need to go mad, just a little more than slightly bending and unbending the knees.
4. As the bar is on a downward oscillation whack the end of the bottom arm with a big hammer really hard as indicated in the drawing. By the third whack whoever is stood on the bar will suddenly be 10mm lower. If they aren't oscillate a little harder and whack a lot harder.
5. Now you can unscrew the retaining nut the rest of the way and the balljoint will obligingly let the arm go.
- Own Work
The Roll Bar drop link:
I don't remember if you were having trouble with this or not.
It looks horrible to get at being horizontal.
1: undo the nut as before, leaving it just on.
2: wrap the hook of a crowbar around the drop link shaft from behind and put the straight end against the rear of the arb so that if you push the end of the straight bit of the crowbar you are applying pressure that wants to separate them. I've drawn another picture as I barely understand that.
3. The arb end looks too delicate to whack so I'd use a spanner in the same manner as a bj separator. I'd beat the hell out of the spanner with the big hammer while applying pressure to the crow bar. The pressure on the crowbar will need to be lots of little kicks, nothing too big but with a fair bit of force and at the same time the hammer strikes the spanner. If you don't have a suitable spanner you could use a proper bj separator.
- Own Work
I'm virtually asleep so forgive me if I've written this in a way that is difficult to understand. I'll check in when I wake up to answer any questions or fill in any gaps.
As the arms similar to a Xantias I could take off a wheel and demonstrate how I'd do it on Sunday if you need me to.
Hope that's of some help.
Don't worry it is not me he is angry with but the "Hillbilly" who designed me. My old tube came out in three pieces with much swearing and hammering (Ouch!!!) but it did come out. Eventually. Except now he has not enough height to fit the new one. The discovery of this brought forth a new bout of swearing.....
I'll be you learned some new English words during that, even if they were a little rude 
