Lucknow

You won't get IET Lucknow with this rank. All the best.

Fill second round of counselling in the second round; you will get it.

To get admission in IET, your rank matters not marks because the level of the paper may vary with respect to previous years' papers but you should try to score atleast 450 marks (under 3000 rank) to deserve some core branches. One more thing that during counselling you should have patience because in last round of counselling you can get a drastically favourable change in your gained choice, however, your rank is more than 5000 many people don't know this thing so that a few get this opportunity. But now you should first revise your syllabus thoroughly and go for mock tests it will really help you to score well.

Cipet Chennai is better than cipet Lucknow. To persue btech in plastic engineering in any sector whether you want persue ppt or pmt

Yes, you can get IET and other government colleges such as IET, KNIT, Bundelkhand university, CSJMU and may be HBTI too.

Yes, 90% chances that you'll get IET Lucknow because lateral entry depends on the vacant seats in second year.

Please mention what is your GN rank because counselling is done by GN rank.

Yes, you have secured a good rank in the entrance examination. There are chances that you can get TUTE, Lucknow for MCA. You just have to look around for the previous year's cutoff of the college.