Just did mine on my 2.6 w201, rears take all of 20 minutes if you've done any brake jobs before, probably 30-40 if you haven't. The uneven wear could be a result of the caliper needing a rebuild, again that isn't difficult if you're half/sorta competant. The discs do appear to be at wear limits and don't appear to have seen an easy life either. Iirc it's a 4mm hex on the drum and a 17 or 19 pair of bolts holding the caliper on. You'll see the parking brake shoes under the disk behind the hub when you pop them off. They look to have been there for a while so you'll probably want to take the caliper off and apply your favorite penetrating oil to the hub flange and the area inside the lug bolt holes to loosen years of rust up. If you find your calipers are in good shape, you'll only have to crack the bleeder and compress the pistons back down before you put your new pads on.

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1993 190E 2.6 Sportline