Investing in shares

Q: Is it halal to invest money in the share market because almost all companies have a debt and/or they invest their money in to debt on which they earn/pay interest. Though the company's base dealing is in halaal.

Burying Islamic literature

Q: With regards to Islamic literature, for example letters and leaflets that contain the name of Allah Ta'ala and the prophet (Sallallahu Alayhi Wasallam), how are they to be disposed of? Is it correct to wipe away/erase those names and then dispose of the letters in the bin, or must they be burned?