I started my commercial cleaning company recently (incorporated, insured) and tried hard to do marketing and slowly picking up clients

Now I have come to a stage that the cleaning work is taking almost all my time(day and night), so I need some help on the operational side. I have hired couple of casual staffs, young males, around 23-25 of age, students. I was hoping they could handle a part of or all my clients' cleaning on their own after 1 to 2 weeks of training, but that didn't workout. They seem didn't like the job because the starting time( usually around 6am) and the travel between clients.

My clients some of them are office, some of them are production warehouse, so the warehouses' office and their lunch room will be messier than the office buildings'. All my clients are all in one suburb, travel time between clients will be less than 5 minutes drive.

I need to know if it is possible to find staff can take over my roll in operational part, what kind of staff am I looking for (age, experience? etc.), and how can I find them?

The amount of money you are willing to pay and the benefits provided will help decide what level of employee you get. 23 year old male college students will more often not be interested in harder work, and are often not dependable ( just don't show up)

Hi Fr Chuck, to your experience, what age group is most suitable for my kind of company? And how can I find out how much salary will give them enough motivation to do the job right?

I am getting average around $30/hour, and doing 70 hours/week, how much should I pay to my staff in order to make them work happy?

Pay depends on where you live.
If you make about 30/hr, maybe 12 - 13 for inexperienced and 15 - 20 for the best.
Advertise for 'experienced help; higher wages.' Check references, wages, and do background checks. When you interview, offer about 60-75 cents/hr more, and more again after a 90 day probation period. They will be your supervisors.
Then you can hire students and inexperienced help, and the supervisors will have to make sure they show up and do a good job.