Miniature or standard?
We have a standard wire-haired - he has a loud, guttural bark which is penetrating and frankly very irritating at times e.g. when recently suffering with a covid headache (but on the plus size a parcel delivery never goes unnoticed). Totally silent once someone is in the house, but complete maniac to anyone who dares to walk past our window...
Toilet training - not terrible in our experience (and would recommend the snip for a boy to prevent scent marking indoors). Miniatures are worse for toilet training apparently and that would put me off - I've heard some are never toilet trained which isn't something I would want to welcome into my life.
Walks - as much or as little as you can give in our experience. As a puppy less was more - I had to carry him back once he was so tired - and it wasn't a particularly long walk but it was mid-summer. Now he's fully grown, he can adapt - longer weekend walks and shorter weekday walks work fine for our sausage. One point worth noting is that ours hates the rain so walks in the rain are very short due to his stubbornness (a key dachshund word). I think it is because the sound hitting the ground is much louder to them...but who knows? Also fox poo - absolutely loves the stuff and can't be trusted off lead on a weekday walk as time does not permit the necessary bath at home. It goes back to their hunting origins.
He is fiercely loyal and a real evening sofa snuggler. He can be destructive - but random, infrequent, outbursts rather than a permanent issue. Sheepskin slippers are not left out anymore.
Watch their backs - although ours tends to fling himself around alarmingly - he isn't allowed upstairs (and can't manage it himself). But if we aren't quick he will throw himself off the sofa/out the car boot - the vet was very unamused when he landed at her feet once during a car park covid consultation. We are careful but our sausage sometimes seems to possess a death wish and he doesn't know he needs to be careful. Vet advised that, unless a genetic condition is at play, the best thing to protect the back is keeping weight off through diet and exercise.
Hand stripping - set aside money for this to be done at least twice a year. It is hard to find a competent person - lots will say they can do it but they really can't. I've paid £25 up to £75 for it to be done. You can have a play yourself but it is never as good as the professionals and ours often ends up a bit lopsided depending on where he has been sat on the sofa when I've combined a bit of TV with grooming.
I wouldn't recommend leaving for 2 days - get any pup accustomed to doggy day care to have that as an option as you never know when you may need cover even if you go down the dog walker route.
And do read up on dachshunds. They aren't a starter breed like a golden retriever - dachshunds are stubborn, intelligent and independent as they were bred to be...the worst thing would be realising too late that you have chosen a dog whose very nature conflicts with your expectations or living situation. Wouldn't swop ours at all but I do sometimes look longingly at the quieter life I had with other breeds...