They can cost anywhere from $20-$50.
There is no fixed price.
Small tips ($2-3) to porters; no tips in taxis; service charges are usually included in the price.
A wall usually cost $1000.
It depends on how long do you anticipate staying at your destination. It usually costs between 4%-8% of the total trip cost to give you a ball park estimate. Consider your factors at http://www.travelinsurancereview.net/tips-and-advice/purchasing-your-plan/what-does-travel-insurance-cost/
The cost varies based on how much the design costs, and how long it is up. However, it would usually cost at least $1800.
Sofas cost money
$350?
Usually $10
You will earn minimum wage, plus tips.
A piano could cost about 100 dollars. (not really sure but that's how much they usually cost)
They usually cost around $1.