Living off the land actually works. No house needed.
As for the Guitar Star accomplishment, that one's been bugging me forever as well. From what I gathered, you need to go to 10 places (or probably throw 10 parties) and perform one of your songs. Not play for tips or just play, you'll actually need to micromanage and click perform, then select a song etc.
I still haven't gotten it though. I got most of the other accomplishments.
Although in the Guitar Star thing requires your sim to "Play in 10 Parties and Venues", it has nothing to do with performing guitar or hosting party. Indeed, it requires your sim to achieve 10 chances that are related to guitar skill. This problem has been bugging for a long time and I know there are a lot of people experincing the same thing. Hopefully it would help you guys to become the next Guitar Star.
In terms of performing, its complicated, i threw a party in the park and started performing infront of crowds, but it didnt seems to count. Im wondering if i can perform at palces like the theater and stadium, i'll have to try again next time
same here ive done 40 now played in parks from party invite played at the football stadium played at the theater played as perform played actual concert nothing seems to get this guitar star working ive run out of ideas now