1.)I'm just wondering about on what grounds will the broker not hire the prospective salesperson? Has anyone ever or known someone who has been rejected?
The only reasons I've seen for rejection are things like dishonesty, racial bigotry, incredible rudeness, or unreasonable demands.
2.) Also, I am contemplating on what to wear.
Wear what you think you'll be wearing when working with your best clients. If you'll be selling ranches and farms, wearing a three-piece suit and a bow tie is probably not required.
3.) I also understand that some brokers provide training. Does this mean that, in normal operations, a new salesperson must complete this training before tackling their first transaction? Or is it sort of a "learn as it comes" thing?
Every broker I've met wants you to begin selling the VERY FIRST DAY you are legally licensed. No exceptions to this rule.
4.) What sort of things should I watch out for and avoid? Are commission splits negotiable and if they are possible, should I do it (I'm fairly new)?
In real estate, everything is negotiable. But as a new agent, unless you bring some incredible inherent value, such as having Paris Hilton as your sister, then you'll have little negotiating power relative to other new agents. Most brokers now are offering better than 50/50 splits.
What to watch for? Start up expenses.
Take all the expenses, fees, dues, and other charges provided by your broker... then double them. To be even safer, triple them.
Good luck!