Can you work for a temp agency your whole life and just have toatal trust in that job if it provides enough for you without any other job.?

I did temp work for a few years. Sometimes the jobs were for seasonal, or a limited time while they filled the position permanently. Sometimes it was extended long term, with an option that they could buy out my contract and hire me after a certain amount of time.

However temp work is not going to be keeping you working 100% of the time. It depends on what requests come in to the placement service.

you assume that the agency will ALWAYS have a job for you, that is NOT a good assumption

It's very rare to have work all the time. You might get a 3 month assignment, then the next month you only get 2 days of work during the month. It's not steady and you never know when you are going to work. You have a better chance if you tell them that you want longer term assignments vs just day jobs. That way you know you have income for a few months

No.

To start, there are laws which say that if you are put into a temp job for a certain time (a couple of years I thinkj) they HAVE to make it permenant.
Usually in these cases, the job just ends, and then you have a period of no work before the agency finds you a new one.