I have studied university papers online, although they were papers from the arts & humanities, not technical papers.
I do not recommend the road you're suggesting. First of all, most distance students drop out with an incomplete qualification, due to human nature (this is taking too long & I've lost interest) and life changes (five years have gone by and now I need to spend more time at the office / in the baby's nursery / in marriage counselling / whatever).
Also, the kinds of places you'll need to go for the first few years do not tend to have academic libraries or other supportive environments. In theory it's possible to borrow books by distance as well, by post, but in practise this is very difficult at assignment time due to restrictive deadlines and everyone else wanting the same set of books.
Sorry to be negative! I've found that it's so difficult to study something after work regularly when it's not directly related to what I'll be doing tomorrow at work. Takes a great deal of motivation, and that's just from doing a one-year equivalent graduate diploma, not even a degree.
To answer your other questions - to achieve B or B+ grades I studied for about three quarters of the time recommended by the college - say five hours per week half the time, ten to fifteen the other half. What to study if not a B.Sc.? Anything that interests you! You can always find a job to match the qualification later, if you need to.
Best of luck whatever you decide though,
O8