Hello,

effect in means you can't choose other stream like Bsc, BA, BBA, BCom any more if you go for BTech once.

there is learning path for every stream. 10th -> 12th-> UG -> PG-> PhD. You have to follow it and it is the rule.

you can take any branch in BTech, it has specialization in Mtech you can pursue it  then go for PHD which is a research area else you can do MBA and join company.

You can choose any specialization in Mtech which comes under your UG branch.

You can go for higher studies but you have to satisfy the eligibility criteria. it is hard to say as i don't know about which higher studies you want know. there are many of streams degree and courses and to get admission there is eligibility criteria or basic requirements

You have to act accordingly.