I could find the answers to your questions on the internet, since the sources are all in german, I will explain the most important things and give you the link, so that you can have a look aswell!
Your first question depends on what "perfect" german means to you. For an "Ausbildung" you don't have to verify your german as you would have to if you wanted to start studying. Nevertheless you have to understand german at least a bit to be able to communicate with the other employees in the company and with your boss.
It really depends on the company and on you, I would say.
All the important informations regarding "Ausbildung" you also find here: http://www.make-it-in-germany.com/fileadmin/content/make-it-in-germany/PDF/MIIG_Ratgeber_Ausbildung_dt_150407.pdf
(it's in german...)
Regarding your second question, I found out, that you don't have to have a certain certificate to apply for "IT-System Elektroniker". You just have to have finished middle school, the rest depends on the company that will employ you.
you can have a look at all the important informations regarding this special "Asubildung" here: https://berufenet.arbeitsagentur.de/berufenet/faces/index;BERUFENETJSESSIONID=wlkwqVIqBdMSLE519OvLxI8FqPWVT9V87jrvz8u3ZxAiKl_6Y8p_!1582604135?path=null/kurzbeschreibung/zugangzurausbildung&dkz=2927&such=IT-System-Elektroniker%2Fin
unfortunately its in german. I wasn't sure weather or not you can understand, but in case you don't, maybe someone can translate it for you.
If you would like to have a look at other "Ausbildungen" that talk about IT, you can type in "Information Technology" in the search box on this internetsite and you will see some names of "Ausbildungen". When you click on the names you will also find all the important information for those certain kind of "Ausbildungen".
I hope this could help you