My travel agent (yatra.com) have booked a ticket with a domestic to international connection at Delhi T3 terminal.Since this is my first overseas trip am confused abt the connecting flights

The flight route is

Bangalore -> Delhi (Jet Airways 9W - 812) -lands at Delhi at 10:30 PM
Delhi - Vienna (Austrian Airlines OS - 34) - Leaves Delhi at 1:30 PM
Vienna -Toronto (Austrian Airlines OS - 71)

All there flights have been booked in a single itinerary with one ticket no:

My questions are

1)Is the 3 hour layover period sufficient for switching from Domestic to International.Both flights with land and depart from T3.

2)I called up Jet Airways customer care and they said they do not do through check ins for the connection at Delhi.Is there a chance they would take up the request at Bangalore checkin

3)Will I have my immigration in Bangalore or Delhi

4)If the Jet Airways flight is delayed who would arrange for alternate flights.
Austrian Airlines or yatra.com

5)If Jet Airways lands in time and I get stuck up in immigration luggage and security,will an alternate flight be arranged and if so by whom.

6)Any suggestions to speeden up the domestic to international change over process

Any inputs would highly appreciated