Tisha B'av

Question

Dear Rabbi, In a previous post you stated that it is permitted to shave after midday on the ninth of Av. Was this a typo - intended to say "tenth of Av"? If not, how can tisha b'av itself be less strict than the shavua shechal bo? 2) Why doesn't brushing teeth constitute washing on Tisha b'av. Is this considered "lhaavir halichluch?" 3) Is the widespread sephardic minhag to eat meat/wine until the second day of Av legitimate? 4) Is there any heter to shave during the shavua shechal bo for business reasons? 5) Is there any basis to the custom not to sit on chairs at home until chatzot on tisha b'av? From looking at the shulchan aruch it sounds like this custom only applies in the synagogue during kinot. 6) Does saying hello count as "She-eilat shalom"?