@IPO MIL JA How were your CA exams? Do share the experience.
1) Regarding your query, yes if you apply 13 lots, chances are very good you receive confirmed 1 lot allotment plus few extra shares as per subscription
2) Expected subscription could be as per estimates any where around 8x-9x
3) If subscription is upto 1x application wise, which seems rarity then every applicant in SH category gets shares
4) If subscription is 13x or above 13x, then it becomes lottery and as explained by CASuraj, happens likewise.