There are two options in it for spouse:
1) Temporary Resident Visa
2) Open work permit
if you are applying for an open work permit then YES spouse have to show satisfactory level of independence as momi said but not a requirement in TRV.
No, it won't affect your application instead you will have a good profile by coming back on time. As far as, I remember I didn't noticed any document where they are asking for previous history.
So, go ahead with confidence
First impression will be "mismatch course"
So, you have to add a covering letter to explain what you explained above to convince the VO that its a relevant course and rest it is good to go.
Farrukh kee pata nahi kia condition ho gee ... hum college walon kee nazrain farrukh kay reply par lagi hoyee hain or dharkan dhak dhak kee awaz kay saath chal rahi hai :D
Yes you should change the course and apply again. Or if you want to apply for same course then you have to justify them with a covering letter that why you want this course and how this is relevant with your background.