Cabin bag need to be within limit otherwise will be sent with ur baggage. No need to worry about the baggage tags, that can be done at indigo counter where they check the weights.
Boarding Pass in phone will be enough but you can generate in kiosk or they can provide you at the counter.
Yes there will be security check in again at the layover airport & you donāt need to worry about collecting ur baggage at layover, it will reach at your final destination.
Donāt carry anything which is prohibited (anything which is flammable is not allowed).
Not sure from where you are travelling but try to reach airport atleast 1.5hrs early to get through check-ins without any hassles.
Other advise for first time flyer:
Keep your govt ID handy.
Cover your ears when flight is taking off (some donāt like that sound & slight pain it causes in ear so).
Use restroom before getting into flight &
Donāt eat heavy food before flying, keep vomit bag (if in case needed, the flight attendants might give u one but to be proactive better to have something with you).
Have a Safe journey. š„³