AUCET

No, it is not necessary if you are carrying an Aadhar card with you.
Best of luck for the exam.

No, you can't join Andhra university without AUCET.

Yes, you can study M.Sc Physics.but you have to crack the entrance exam tancet conducted by Andhra univ

No, there is very less chance but if you contact them, then it may have some solutions.

There are many universities offering this course, but you have to opt one from them. I would suggest you to join IGNOU. Search IGNOU study center nearby and get the details from there. Go to UGC DEB website and download recognition list. Andhra University doesn't offer the same. Regards.

For B.Tech, you need to give EAMCET. For B.Sc, AUCET should do.

All the candidates who have secured atleast 50% (45% for SC / ST candidates) marks in group subjects of the qualifying examination fulfill AUCET 2018 eligibility criteria for science course admissions. It may be noted that AUCET 2018 exam for science courses is mainly conducted for five papers:
Life sciences
Physical sciences
Mathematical sciences
Chemical sciences
Geology
Here are more details:
https://www.shiksha.com/university/andhra-university-visakhapatnam/exams/aucet

AUCET Syllabus 2018:
Andhra University prescribes elaborated AUCET syllabus for each paper. Please Check for AUCET 2018 syllabus for your subject from the link mentioned below:
https://www.shiksha.com/university/andhra-university-visakhapatnam/exams/aucet/syllabus