Applying for two Schengen visas at the same time

You will need to adjust your travels plans as there is rule that in any 180 day period you can be in Schengen area for maximum of 90 days (source: https://travel.stackexchange.com/a/21461/12462 ) Your stay in Norway and Austria are 102 days in total. They are separated by 15 days stay in US but they still in same 180 period so you need to shorten you stay in Schengen area from 102 days to 90 days.

I entered your travel plans into this official caculator http://ec.europa.eu/dgs/home-affairs/what-we-do/policies/borders-and-visas/border-crossing/schengen_calculator_en.html and result is "Days of stay in the 180-days period from 29/04/16 to 25/10/16: 104 day(s) Overstay in the period from 12/10/16 to 25/10/16 (14 days)"

If you have both visas "Visitor" like "Visitor general" and "Visitor - study" then you need to change your plan a bit.

If you second visa is "student" not a "visitor". You should be able to apply for both visas now in advance. 90 days rules should not apply to you, as your second visa is "student".

You can not apply for visa in US, if you will stay there just for 15 days.