CAT

Hi Swapnil ,
The decision depends on you. If you are targeting CET Exam only then definitely, you can work and prepare for it simultaneously. For CAT exam, you need to dedicate some more time compared to other exams. If you are working hours are good enough and are providing you ample time for CAT, then go for it. Otherwise, you need to take a year gap for dedicated preparation.
Your decision will depend on the colleges you are targeting.
I will be glad to clear your doubts.
Hope it helps.

In India, lot of entrance exam conducted by college other than CAT/MAT are XAT/CMAT/NMAT/TISS/X-GMT/MICAT and several other state level test.

No, without CAT admission is not possible in IIM. It is compulsory to attempt it for admission. You can go for private colleges for admission if you have not given entrance exam. Thanks!!

It is good for CAT only not for XAT.

At 50 percentile it will be difficult to get top tier colleges. You can look for one more attempt for CAT and other MBA entrance exam. At this score you may try for state engineering colleges MBA department. You can also look below link for this year colleges predictor-
https://www.shiksha.com/mba/resources/iim-call-predictor.

No you need to prepare for GK as well. There is sectional cut off for GK in IIFT. Yes, preparation for CAT and IIFT is similar. You can check the syllabus for IIFT on below link
https://www.google.co.in/amp/s/www.shiksha.com/mba/exams/amp/iift/syllabus
Also check this link-
https://www.google.co.in/amp/s/www.shiksha.com/mba/exams/amp/iift.

You need more than 95 percentile in CAT to get a call from IIM.

State entrance exams may help you. According to government rule for MBA atleast 1 competitive exam scorecard is required for admission.

You need to attempt a specific number of questions correctly. However, you need to overcome the situation where you are performing well in one section as compared to other due to the paucity of time. You need to look for questions taking less time to solve. This comes through regular practice. Join a good test series and evaluate your performance.