How is a digital certificate generated?
Plain text of data, including server's public key
  


Yes, and many other public information, including something identifying the holder of the public key (perhaps in the Common Name field).


  
  Signature of hashed version of plain text
  


Yes, except that the correct semantic is: Signature of the plain text. Building and verifying the signature includes hashing plain text.


  What encoding scheme is this?


See RFC&nbsp;7468 section 5 and what it references, including RFC&nbsp;1421 section 4.3.2.4 for the translation of binary to text (which in a nutshell is per Base64).


  Does this offer extra layer of security? 


From a cryptographic standpoint, no. That's merely a binary-to-text encoding, see this for rationale.


  Shouldn't the main ideas (point 1 and 2) be secure enough?


Yes, they are.


  Is there a way I can break this blob down to visually show that data part and the signature part?


When there's any non-confidential piece of standard text-encoded stuff to decode, it can be thrown at the marvelous https://lapo.it/asn1js/ (with or without the delimiters) and the results are usually pretty good. When in doubt about the confidentiality, use a local copy in an isolated VM.