How easy/difficult are both the minis and standards to breed?
Do they generally struggle to mate and are shelling difficulties/c sections common?

Any info appreciated as my friend is thinking of breeding and I want to give her info (she would do things properly, but has never bred before and I want to give her a realistic idea of what she could expect)

Thanks

I dont know much about dachshunds but id first get your friend to get all nessesary health tests done and make sure stud is health tested also, i have a friend who bred her dachshund and 1 of the puppies was riddled with health issues and has recently had to be pts at only 3 years old costing his owner £1000's in his short life this was because she never had the necessary tests done before hand.

Standard Dachshunds don't require any health tests, all 3 coats of miniatures must be DNA tested for GPRA (cord 1) in addition mini wires must be tested for Laforas. One parent must be a clear, a carrier is fine as long as put to clear, affected should not used for breeding.           

I've never experienced any problems with Dachshunds mating, they are more than capable and willing!

I wouldn't say c-sections are common, but it is always possible for any breed to run into problems and require one, so you would need to be prepared for any eventually.