I'm a Keller Williams agent and will be happy to answer any questions you might have either on the board or by PM.
I see no reason why anyone would discourage you from working as an assistant if that's your goal at the moment. There are many facets of this business and some find themselves enjoying different roles. And yes, MANY top agents hire assistants. But remember, being an assistant to a top agent might take more hours out of your day than most new agents starting out on their own put in! (That's a good thing, right!?) Being an assistant to a top agent would give you some insight into how things work. And you may choose to become a dedicated buyer agent, a listing specialist, a transaction coordinator, or even hire on with a broker's staff. There are endless opportunities!
KW is great, btw. When I was shopping around for a new broker I heard so much misinformation about the company. So always check out a broker for yourself. Schedule a visit and meet with the local manager or team leader. If another broker or agent tells you to 'stay away from so-and-so' it may be because they know once you go over you'll not come back! That holds for all companies, btw. Most agents think their company is the best fit for them. So we're all biased. Don't take my word or anyone else's word... go schedule visits... meet with EVERYONE and find out for yourself!
Good luck!