I dont know about HDFC Investment Service Account, but
IF its like ICICIDirect (seems so), then they act as distributers and get extra from expense ratio. In that case you will not be able to buy DIRECT versions of MF schemes that have lower expense ratio.
Do consider Direct MF instead of non direct. Over long periods, the 0.5-1 % expense difference will have double compound effect - 1) expense itself 2) Missed returns on that expense.
With a portfolio of say 50L, if we assume expense difference is 0.5%, you would be indirectly paying 50k EVERY year to Distributor. So its not free.
Once setup, I didnt find anything missing vs ICICI direct. You can get consolidated statements/transaction reports from
CAMS/Karvy