Institute of Engineering and Technology (IET), Dr. A.P.J. Abdul Kalam Technical University

Yes, you can get IET and KNIT both, but not BIET.

Yes, you can get admission in IET on the basis of your SC rank.

Yes, you can get the desired college with your rank.

I don't think at this rank, you can't this college because it depends on vacant seats. Probably has a 30% chances.

Yes, you can get admission in IET at this rank. All the best.

No, you cannot get a government college with this rank.

Yes, you can get gov colleges and there are 50% chances for IET.

Here is the seat matrix for IET Lucknow. You can get admission here:
Chemical Engineering 60
Civil Engineering 60
Computer Science and Engineering 60
Electrical Engineering 60
Electronics and Communication Engineering 60
Electronics and Instrumentation Engineering 60
Information Technology 60
Mechanical Engineering 60

If it's about placement then you can go for CSE, you can choose any of the colleges mentioned above. Anywhere CS/IT students get easy placements.
If it's about location. Lucknow is much better than Sultanpur in all aspects.
IET-Lucknow has a better campus than KNIT. Well, finally it all depends on your interest. As you already passed out 12th and if you're from CBSE board, you have already studied computer in last two years (I know it's option, but then also )
If you want to go for government jobs, just go for civil engineering, if you want to work in private sector, go for CSE.