make it in odd numbers as per vastu, width 3ft to 3.5. step height 6 to 8 inch step depth 9 to 11 inches

When dimensioning a classroom or teaching space, the best rule of thumb to produce both good sightlines and efficient layout is as follows: the space needs to be slightly rectangular, but NOT long and narrow. If X = 1, then Y should = 1.2 ideally, and no more than 1.5. Consider a comfortable space of 12 sqft. per student so if you have 6 students in a classroom then 72 sqft. + teaching space and walking space (60 sqft. or more) so say roughly you need 130 - 140 sqft. of space per class.

It depends on various factors like the size of the building, distance between pillars, and floor to floor height. But yes, as Joitree says, this is not something you can just find online. You have to consult a professional structural engineer

Hi Shivam, I hope you are doing good. There is no particular tile size that may look good as it completely depend kind of design you have in your perspective. If you are looking at more traditional interiors then generally smaller tiles with motifs or emblems look good which have a representative geometrical or floral patterns. If you are looking at more modern interiors then generally bigger tile sizes are preferred for clean look less joints.  Regards, deSigneR