Here is the answer to ur questions.

Regardless of whether ur resident or non resident,

standard ded including personal exemption: for single is 8750, meaning if u make this or less than this then u will get all federal tax back, state limitations are different.

if u r in OPT-no ssn or medicare tax

if u r in h1b, greencard or us citizen=pay all taxes

If u r here in the usa in nonimmigrant visa for less than 5 yrs=file 1040 NR , that is the only rule.

183 days rule might be for MA ...this might not even be for nonresident, it might be for us citizens & residents allien ...can't help here ..not fom MA

183 days rule that doesnot apply to any federal tax. only 5 yr rule.

Most of the foreign students file 1040 EZ or 1040 eventhough they r here for one semester..i personally do not suggest , my professional integrity, but ppl get more refunds for filing as resident cauz they get tuition credits as mentioned below.

 meaning u can deduct tuition fees and get tutiion tax credits. ( only if u paid for it, if u r in scholarship then u did not pay for it so u can't get it back, mind u some scholarship are not tax exempt meaning u r required to pay taxes on that)...this is tax if there are 100 rules then there are 101 exceptions..don't get into it unless u want to ...

Hope credit upto $1650 for first 2 yrs & lifetime learning up to $2000 per year after 2 yrs of postsecondary school.

These credits are not refundable so u can't get the money back unless u paid tax. u can only reduce ur tax liability..The general concept of "geting back" is misleading....

reminds me of newton's 3rd law of motion: every action has equal N opposite reaction.

if ur money caused some action, u will get it back through some tax reaction......no action no reaction...

have fun...