1. Front struts - I used a second jack (instead of the spring compressor). It worked fine. All you need to do is raise it slightly--not enough to compress it. The best resource is the W124 Front Strut Replacement DIY article on this site. Make sure that you have all of the right tools and then just take your time.
2. Differential Fluid - My differential has 14mm hex filler and drain screws. Make sure it is warm, then remove the filler first, then the drain. There are several ways to fill it; I detailed how I did that in a previous post.