Outside Maharashtra students can appear for MHT CET. Outside Maharashtra Student won't be eligible for Government and Govt. Aided colleges, they will be eligible for All India Seats of Private colleges. However All India Candidature candidates may or may not appear for MHT-CET 2018 as Score of JEE(Main) Paper I shall be preferred over MHT-CET 2018 for admission to B.E./B.Tech.

You can also check the further information with the given below link.

Yes you cn definitely apply via OMS Category for MHTCET seats into Engineering streams. 

Around 15% reservation is definitely reserved for OMs Category.

All details shared below. 

https://engineering.careers360.com/articles/mht-cet-counselling