There have been four previous Saints honoured as Jagadguru before you. Who gave them the title?
During ancient times, there was no authorised body of scholars like Kashi Vidvat Parishat. Instead a process called shastrartha or scriptural debate was used, whereby established great scholars debated with the prospective Jagadguru. Ultimately, the winner was one whom all the scholars accepted as supreme, and therefore, Jagadguru.
In this present age, however, the prevalence of undeserving persons declaring themselves to be Jagadguru is rife. In such circumstances, the need for a body of eminent scholars all well-versed in the scriptures was paramount. Such an assembly could then be widely accepted as being qualified to judiciously decide upon the suitability of a candidate before any title is conferred.
Shri Vallabhacharya and Shri Chaitanya Mahaprabhu were also great scholars. Why weren't they honoured with the title of Jagadguru?
In order to be eligible for this title, one has to be both a great scholar of scriptures and God-realised. There have been many God-realised Saints in our history who had complete knowledge of scripture, yet they did not manifest that knowledge publicly, nor did they ever covet the title of Jagadguru by subjecting themselves to stringent scriptural debate.
What is bhajan?
Bhajan is nothing but service of your Beloved God and Guru. You can truly serve your Beloved only when you love Him intensely. Love becomes intense when the feeling of belonging to Him gets stronger. This feeling of belongingness is considered strong only when you stop thinking about your happiness and think instead about how best to serve your Beloved. This is sadhana in the true sense of the word.
Original answers given in Hindi by Jagadguru Shri Kripalu Ji Maharaj