The third bullet is the important point.
- Can I enter Germany as my first entry point now ?
It is 100% OK to enter through a different country to the one that granted your visa. This is totally normal and fine.
- Are there any stamping issues associated with that during the Immigration check in on Airport?
No. You have a schengen visa and you're entering schengen, This is fine.
- Based on my current itinerary I'm spending more time on Germany and Austria than France , again would it become a problem ?
This.....is potentially a problem.
Spending more time in Germany and Austria- does this mean more in both of them?
e.g. 10 days Austria, 10 days Germany, 2 days France?
That situation would really ring alarm bells and may lead you into trouble unless you have a very good excuse.
Or do you mean more like Germany+Austria: 8 days, 3 days Germany/5 days Austria, and 6 days France- thiw would be fine and not considered abnornal. You can only get a schengen visa from one place afterall.
If its more like the first one but the difference is 8/7/6 then that would probably be fine. You may get questioned but if you explain France is the main purpose of your trip or plans changed or whatever, then it should be fine.
But if there's a huge unbalance between where you claimed to be going when you asked for the visa and your actual plans...that will seem strange and may lead to trouble,
- Will there be any problem when I apply schengen visa through french embassy in future ?
This totally depends on the 3rd one. If the 3rd one leads to trouble and especially deportation this will massively impact any future attempts to get a visa through any european embassy. Nothing specific for France however, unless the same people are working there and they remember your case.
If however you have slightly more in the other two and they let you in without issue then it won't be an issue in the future either,