Not being funny here, we don't know you from adam, we don't automatically know what experience you have, or how long your tank has been set up.
SO
We ask questions to ascertain the answers.
If you are going to come on here and insult people that try to answer your original question, you are going to get the responses that you have done.
They are basic questions that are asked of anyone who posts a similar question, sometimes even if we know what stock they have as they have a journal on here. It makes a thread worthwhile and usable to someone searching for the same answer.
I have a pair of Mandarins myself, I have a culture that has been going for less time, mine both also eat frozen, which I trained them to do.
You are better to try to find a partner that has taken frozen food as this will be easier to work with should your culture crash for any reason.
You should in that size tank have more than enough rock for one and possibly enough for two.