Use a search and look the forum up, unless thats not working for you mate, which sometimes happens to me (ISP issues). Other than that a lof your queries are answered in other threads! I germinate then use rockwool, but during the seedlings until they sprout I was informed by Serapisis (apologies if name is incorrect) to leave dome over until they sprout then remove it for various reasons, including mould / algea I think.
Apologies if incorrect in the micro detail, but his main point was leave dome on them until they sprout then uncover! Credit to Serapisis for the info, I'm recycling it!