Is the job in demand?
Yes, the job is in demand.
Is this an enjoyable job?
"Enjoy-ablilty" of the job is relative. I won't go into the personalities that are drawn to the legal industry (by "personalities" I mean attorneys) whom as a paralegal you would serve (and I do mean serve). I don't have enough space, time, or energy to cover that here.
What are some of the things you have to do?
Some of the things that paralegals do are actually very administrative in nature, especially now that the economy has fleshed out many non-essential workers. So in smaller law offices, the absence of administrative staff and receptionists may add pressure the paralegal to perform admin duties lickity-split in order make more time for substantive work, especially in cases where the paralegal's time is charged back to the client by the attorney. If you are shy to ask if the attorney is billing your time, simply check your hand mirror. Is the attorney peering over your shoulder? If yes, the attorney is probably billing your time. Think "micromanagement".
Besides that, other things that a paralegal might do are.....well, lots. There are many websites that discuss duties and responsibilities of paralegals. Here's an address to LawCrossing and its brief discussion on the subject. http://www.lawcrossing.com/article/4906/Becoming-a-Paralegal-Do-You-Have-It-in-You/
What is the salary range?
Salary varies wildly. (Yes, wildly.) For instance, in a single law firm an entry level paralegal who started a month ago and is fresh out of school might earn a salary that varies from that of a paralegal who started out as a mail room clerk five years ago. So, seniority could be a factor. Similarly, the salaries of an in-house (or "corporate") paralegal and a paralegal in a law firm, both with ten years of experience in litigation, could differ dramatically. One sure-fire reason for that - corporations pay better than law firms. (Most paralegals will corroborate.) Another thing, salaries are lower where cost of living is lower. Yet another thing, the title of "Legal Assistant" (as opposed to "Paralegal") seems to go hand-in-hand with a lesser salary. Also, revenue of the organization are huge factors in salary of employees. Things that affect business revenue are location and age of the business or firm, and attorneys' experience, amongst five billion other factors.
To give you some idea of the variation of salaries though, I have seen a want ad for a "Legal Assistant" (as opposed to a "Paralegal") offering $10.00 per hour. The duties and responsibilities of the position, based on the ad, were on the level required of many paralegals, and this wasn't twenty years ago but more like twenty days ago. (Yes, I know.) On the other hand, several years ago I read about a paralegal in the eastern part of the U.S. who, at that time, earned a six figure salary. Obviously, she had a ton of experience, but hopefully you can see what I mean about variance.
Is it hard to get into a law firm?
I don't know, really. I don't try to get into law firms. I have done that and found that I would prefer to cough up hair balls. In my opinion, firms come across as heavy on process and bureaucracy and light on professional development and quality of life. My preference is to work on my own as an independent paralegal. (I actively pursue opportunities for growth towards that end.) As I move into that, I try to work with smaller organizations who's interests I care about and who care about my interests too, and where the employees know my name. (These are almost impossible finds in law firms and large corporations.)
As you consider the ITT course, I hope this helps and answers your questions.