Welcome to Canreef.
Seems to me you've done your homework
Keep up the good work. Both T5 and PC will give you the light you need for zoas and mushrooms, ( which happen to be my favorite as well ). On the buy/sell forum you can post "looking for" t5 or pc light source for your 20gal etc and see what kind of response you get. You never know what may fall into your lap.
Live rock imo is almost the coolest thing in your tank. If you buy from a store and let it cure in your tank, you will see all kinds of neet stuff growing and crawling off it. First day there won't be much but by day 30 there is usually some pretty cool things happening. Small snails, little feather dusters, etc etc. Before and after pics are great for that.
Don't be freaked out about starting the tank. There is lots of help hear on Canreef and as a teacher you should know we learn from our mistakes. LOL.... Aptasia and flat worms etc happen in this hobby but there are ways to take care of it all. So don't worry too much about what might happen with regards to that stuff. Take your time and ask lots of questions. Hey wait a sec, that's what your doing. :/ Make a list of what you need / want and start from there and have fun.
I'd say your on the right track.
Cheers
