I am guessing that you mean a Plecostomus. The answer is NO. Each of the species needs totally different conditions. Goldfish are cold water fish and suffer when the temperature goes over 75F. Plecostomus are tropical fish and suffer when the temperature goes below 75F. They will both survive for a while in one anothers parameters but eventually they will die from living in the wrong conditions.
goldfish do not live on land
For househeld goldfish, they generally live 6-8 years
Your goldfish will not live "longer" no matter how many or how few you have.
yes
No, goldfish are freshwater fish.
depends, can a ten gallon tank live in a goldfish
No, goldfish are best with goldfish. In addition, tilapia have different needs and are quite likely to be aggressive towards the goldfish.
A goldfish is a freshwater fish, and as such does not live in the sea.
Goldfish are egg layers
no the goldfish would it the tadpole
No
No