IIT

it is there on the website

HelloNo , If you want admission in IITS for MSC then you can not fill any type of form now, because IIT- JAM 2016 is already conducted on Sunday, February 07, 2016.
IIT JAM 2016 invites applications from eligible candidates for admission to M.Sc (Two Years), Joint M.Sc - Ph.D, M.Sc - Ph.D Dual Degree, M.Sc - M.Tech. M.Sc - M.S (Research) / Ph.D Dual Degree and Other Post - Bachelor's Degree Programs

Type of board does not matter for results of IITs or NITs. +2 score is used as minimum eligibility criteria. There are changes expected on eligibility criteria for 2017 batch.

You should be more clear about your query.

U can compare colleges of Aerospace engg. by using option on shiksha which will give u whole information about the colleges in which u want to took admission and u can also compare colleges.

For MTech you have to crack the gate and then u can get admission for MTech u directly get admission for Mtech if u have completed your Btech from iit.

ofcourse u can do that. if u don't want to appear for iit jee exam den go for upeseat by which u can get admission to india's 3rd top institute upes dehradun for petroleum engineering after iit bombay nd ism dhanbad. its placement is very good. go for it.
best of luck

Jee Main marks doesn't really matter in iit admission but you still have to clear cutoff in order to sit in jee advanced which was around 80 marks out of 360 in 2014. As far as Advanced marks are compared the closing rank was around 850(OBC) category which means 170 marks out of 360 around 47% .But all these stats are from 2014 IIT JEE exam and changes every year.