The original image you highlighted appears to me to have been taken at around 150-200mm (FX equivalent), from the flat perspective and limited depth of field it's showing. The second one - not quite that long, probably 85-135ish I'd guess. Remember that depth of field decreases with increased focal lengths as well as wider apertures.

Now, for a group shot with a long lens like that you need space - that photo certainly couldn't have been taken in the space available in most homes, you'd just need to be too far back.

So -

• Faster (smaller f number) lenses always allow shallower depth of field than slower versions
• Wider (short focal length) lenses will always have more depth of field than longer. No matter what I do, a 12mm will have more depth of field than a 300mm.
• Wider lenses tend not to be the most complimentary for portraits. Partly distortion into the corners, more that they emphasise front to back differences in scale that longer lenses flatten and so tend to give subjects large chins and noses!
• Long lenses make the background larger and softer, wide lenses make it smaller and crisper.

If I wanted a basic starting point lens to let me get portraits like the image you've highlighted, I'd pick up something like a 50-200 or 70-300. In decent light it'll be quite sharp enough, it'll let you get the sort of depth of field and perspective that your image shows, and they're cheap, light lenses so easy to work with. If you're set on primes - from that list an 85 f/1.8 will get reasonably close to the look you've highlighted (particularly on a crop sensor camera), it's just more expensive and less flexible with fairly minimal practical advantages in this case IMHO.