Yes, a good idea, using Moodle. Moodle is used for a whole range of academic, professional, business and artistic learning, from the Open University to Mother McCready's Home for Wayward Boys and Girls.
Going from last to first question:
The Certificate plugin will allow you to produce, automagically or manually a certificate of attainment, produced when the USer has successfully completed all the required learning outcomes, or objectives, standards or whatever you want to call them. As long as the Certificate is recognized as being a valid award for achievement, then there should be no issue about receiving credit earned.
Tracking can be achieved in a number of ways. Self tracking progress can be achieved by including the Progress Bar on each course. This allows the User to track their own progress through an individual course. As each course is successfully completed, notifications can be automagically generated at the same time as a certificate, to be sent to someone who is supposed to know what that user had done, usually their course teacher, or contact person. That person can then follow that up as they normally would. There is real risk, I suggest, in trying to completely automate this aspect of any learning process, it is too easy to circumvent even with the best security protocols.
Tracking attendance by time in and time out is a matter of tracking the actual login and logout times. This is a record in the database of "Time of Last Access", but it is not, never has been, and likely never will be, successful. I don't just mean in Moodle, I mean in any system. The reasons for this are multitude, from simply forgetting to log out, to power outages, to anything else you can think of. The hardest part of tracking by time in/out is there is no guarantee that the User is actually at the computer, doing the work.
You can login, go and make a coffee, sit at the computer and surf the net, finish the coffee, make a pit stop, surf the net some more, oh, then work on an assignment, go get lunch, surf the net, make a coffee, surf the net, work on the assignment, log out satisfied with a good day's work. That is depending on the fact that it is you logging in and not the guy you paid 20 bucks to log in as you for a couple of hours. Alternatively, a User logs in, downloads a couple of assignments, logs out in a few minutes. A day later, uploads the completed assignments and repeats the process. All in all, the User has spent less than an hour in the course, but had achieved a lot more.
Tracking by time in/out is a risky and inappropriate way of tracking a user's commitment to the course. I would go one step further and suggest that anyone suggesting this kind of tracking either has no clue of what they are talking about or are being deliberately mischievous or outrightly lying to make a sale. Be wary of any such claims.
As someone once said, the proof is in the pudding, so if someone has successfully completed all the required tasks, then chances are that they have actually done the work, so should receive the credit.
The only time that tracking by login/logout is even remotely likely to be successful is if Users are in a completely controlled environment, even then you can note that Users will likely get around restrictions, but GLWTOB!