If you live right next to a busy traffic road then your outside cat may very well be hit by a car. I've seen it happen a million times to others....and for some reason I have yet to figure out, they always seem surprised when it happens. (hello?....)

Younger cats (less than 2 perhaps?) can be generously praised when using their scratching posts (hint, cats especially like TALL scratching posts or cat 'trees' with sections of sisal rope and carpet). They can be discouraged from scratching furniture if you keep an eye on them. We managed to train our cats to 'mostly' not scratch the furniture- gave them much better things to scratch on and praised them when they did good.

Old fashioned clay cat litter tends to smell a lot. There are many new alternative litters that are way less smelly- and of course if you offer a decent sized box and CLEAN OUT the deposits in the box every day, then there is not much there to smell- especially with only one cat.

As to 'being a PITA'- well not much helpful advice i can offer there, except that maybe he is not a good prospective cat owner?