Check at http://siahub.info/ for a list of hosts. Click on the "score" column and hosts will be ordered according to their rank. That way, you can check what the top hosts are doing.
Your goal should be to stay among the top 50, but the higher the score, the more chances to be selected when a file contract is formed. Right now, most hosts are targeting at the $1-2/Tb/month storage rate. Your collateral should be 2-3x your storage rate. Bandwidth costs should be lower than the storage price. You'll need a big collateral budget if you have a lot of TB to offer. If you offer less than 4Tb, you will be penalized on the final score
In general, I recommend you to go the the Slack of Sia to ask more specific stuff. We are a lot of hosts there ready to help :-)
It has been disabled for about one week. Sia devs are working with Poloniex people to fix it. They catch the bug already, so it should be done very soon.