1) For a trio of green anoles i'd recommend something like an 18x18x18 enclosure. For a trio of knight anoles I don''t know an exact size but I used to have a forum friend who kept and successfully bred a pair in a 55 gallon screen reptarium. So Maybe a size up from that.
2) Pothos are a great plant for an anole viv since they are hardy and grow fast. Plus anoles are light enough that they can climb on them without damaging them. I assume you mean Ficus benjamina when you say ficus, which is another great plant. Other plants I'd recommend would be snake plants and draceane for something to climb on, and philodendron and African violets for decoration and color.
3) Anoles are basking lizards, so they'd prefer a basking light with UVB as a source of heat rather than an under tank heater. Hot rocks aren't as bad as they used to be but again not good for anoles. The basking temp should be around 95 degrees.
Hope this helped, feel free to ask anymore questions!
