First of all, being a lead is not you in competition with your juniors. Everyone of us have different experiences and different starting points.
IMO It is helpful to remove the "senior" or "junior" title when working with them.
Work with them.
Provide guidance when needed.
Learn from them.
Trust them.
Consider their opinions.
Help them provide you with information on things you are not familiar with.
Praise their accomplishments in public.
Critisize mistakes in private. Provide useful feedback
I wanna say "There are no best tech stack". It all depends on your use case.
What language are you good at OP?
You can quickly mock up majority of your use case using PHP, ruby or even Node.
Create a monolithic app and stay away from microservices until you have clearly drawn service boundaries. I'd say (6 to 12 months) in production. You dont need the headache of the distributed overhead.
Just keep in mind that you should "write code that can easily be disposded or replaced, not extensible"
For generating client sdk's i suggest using swagger. Grpc is there but i have trouble grasping protobuf sharing at the moment
For user clients, i would go for react native.
You're better off using a 3rd party for analytics when you are starting up: if you have the money, I'd suggest using segment, new relic or even google. Else, do it with prometheus or kibana.
https://hackernoon.com/an-organized-chaos-5c844f8a9c82?sourc...