Thanks for the photos John. If I read this correctly you're asking about using a 1.5 oz suede to repair a 4 oz item with one of the rips across a seamline. That's gonna be tricky since it's in one of the highest stress point areas for trousers.
First off conditioning. I haven't done much with suede myself but from digging around I can offer you a few leads. For cleaning and general fluffing you can use a suede brush or a pencil eraser. For conditioning I've found reports on Neetsfoot Oil, Scotchgard, wiping it with a rag soaked in a one-part vinegar to three-parts water solution, using a sponge with liquid silicone, taking it to a dry cleaner, or rubbing cornmeal into the material before brushing it off. Regardless of what you do test any process out on a spare bit or material, or lacking that a small inconspicuous spot on the item itself.
Personally I'm intrigued by the cornmeal suggestion and am tempted to do it with a friend's also hardened vintage pair of lederhosen myself. The last stages of buckskin tanning requires you to work [knead] the material over to break down the hardened fibers and I wonder if a similar process with a softening agent might result in revitalization with suede.
Next, the material itself. 1.5 oz leather - suede especially - is fantastic for lining. I wouldn't use it for the sole lynchpin of a repair other than as a cosmetic fix though. If you can get a 2-3 oz suede that matches the lederhosen use that, otherwise I'd suggest doubling up the 1.5 oz.
The long tear on the front should be the easier repair - you'll be able to patch it up like one would a pair of jeans. And since glue sticks extremely well to suede be careful when applying it so you don't get any where you don't want it. Once the patch is glued in place a baseball stitch in a matching color upholstery or waxed thread should secure the rip nicely.
The hole in the back however... If this was my own project I'd be sorely tempted to replace the welt entirely. Since it's in a relatively hidden location you might be able to get away with a smaller adjustment. I'd tear out the stitches for about one to two inches on either side of the rip, patch up the holes like on the front (one patch for each side of the seat), then re-sew the seam back together with a new welt overlapping the old cut from a matching material out of at least 4 if not 6 oz suede.
Barge would be the way to go; you'll get the best tack for your buck. I'd avoid the Toluene free glue since it's not as strong unless you can't get the other stuff. If neither of those are available and you're using Tandy's go with their Contact Cement over the Rubber Cement - it'll last longer.
In checking through my lederhosen reference library I didn't find much regarding traditional embellishment in the regions you're looking at repairing. Some varieties of leather pants have ornate embroidery going on - which could be used to hide and even fortify patchwork - but almost all examples of this I found were around the waist and on the outer thigh portions (see pics).
Also, check out the hosenträger for rot and the like. It looks like the backing has rubbed off in a few areas. If they're dry and cracking on the grain side I'd encourage you to consider replacing them.