Tieflings are often met with distrust by other adventurers and fear from some townsfolk. People in larger cities are more likely to be accepting of people on an individual basis, but townsfolk from small villages are more likely to be hostile and scare easily. Of course, since the campaign takes place mainly in Waterdeep, and our last tiefling character didn't have a hard time, I wouldn't expect that the next one would either.
Yes, though if you want to use the lesser tiefling or lesser aasimar race, or use level adjustment buyoff, those options are fine too.
There will be as much or as little sex in the campaign as the players/characters want. Ultimately, they haven't had much down time since the campaign began, but the discussion about sexuality was mainly to get the characters as fully realized as possible before we started playing. The campaign won't revolve around sex, and since the problems the PCs have to solve are somewhat immediate, the opportunities for sex will really only be at brief periods of downtime.
The post rate of the game (when it's steady) is a DM post every few days (with luck, 2/week) with player posts in between. In combat, I try to get a post from everyone participating in the combat once per day (or 48 hours, as the case may be) so that we can move it forward quickly.