Explanation:

The Model Code of Conduct consists of a set of guidelines expected to be abiding by the political parties, their campaigners and the candidates. 

• Objective: The Election Commission brings the Model Code of Conduct into effect to ensure free and fair elections.
• No judicial enforcement:Though the ECI does not have a judicial ability to penalise the violators of the Model Code of Conduct, it generally issues show-cause notice to the violators and in some cases, bars them from the poll campaign.

Star campaigner

• A star campaigner is a celebrity vote seeker in an election for a party. This person can be a politician or even a film star. There is no law governing who can or cannot be made a star campaigner.
• They are nominated by the concerned political parties specifying their constituencies and duration of the status.
• A ‘recognised’ party declared as such by the Election Commission -- can nominate a maximum of 40 star campaigners.
• An unrecognised political party can nominate a maximum of 20 star campaigners.
• Expenditure incurred on electioneering by the star campaigner is not added to a candidate’s poll expenditure giving him/her more leeway. 
• According to the Representation of People’s Act, these expenses will be borne by the political parties.
• For an individual candidate to get a relief from campaign expenditure, the star campaigner has to limit oneself to general campaigning for the party.

Prime Minister as Star Campaigner: The MCC guidelines say when a prime minister or a former prime minister is star campaigner, the expenditure incurred on security including on the bullet-proof vehicles will be borne by the government and will not be added to the election expenses of the party or the individual candidate. 

Hence only statements 2&3 are correct.