Finishing my BSc while working - asking help to professors and future academic chances
I`d like to know how does such a twisty academical career affects my chances of getting accepted in a good Master program around 2 years from now.


Overall, the point of the admissions process is finding candidates who will succeed in higher study.  Your ability to overcome obstacles to get a degree, as well as your success in industry, both provide evidence that you will also be able to tackle a master's program.  Overall, your story is a positive one.  Taking a long time to complete a degree won't matter at all under the circumstances.

If there are some slight negatives to your story, they are:


Low GPA this does matter, but how much is dependent on the institution.  Also, your success in non-academic activities may offset this somewhat.
Will you continue to struggle to have time for your studies in the master's program?  This is something admissions committees may worry about.  If the circumstances that caused difficulty are going to change (for example, you will stop full-time employment in order to get a master's degree, or the family issues have now been resolved), then you should be sure to amke that clear.  



  what is a legitimate level of "help" that I could ask for to a
  professor of a mandatory course that I am finding extremely difficult


There is no harm in asking the questions that you suggest.  Your professor can always say no if they don't want to provide the information.  Also consider simply going to your professor and saying "I'm finding this class extremely difficult, are there any resources I could take advantage of for extra help?"