Missed Deferral Opportunity and 402g limit and General Testing

[DLMRetire]

Participant elects to defer 3% of pay in 2015 and employer doesn't implement election fro 10 months. 3% of pay equals $10,000. Employer does applicable notice to employee and deposits $2500 per 2015-28. No match.

Questions: Can employee defer add'l $15,500 ($18,000 less $2500) or are they limited to $8000 (18000-10000). IRS Webinar from a while back seems to say 402g limit is reduced by missed deferrals so i'm thinking participant limited to $8000 but cant find anything really concrete on this.

Also, does the $2500 count as employer contribution in general test. I think not, but again, cant find anything concrete on this.