Ok I have some questions regarding some order types.

What are the differences between a LMT, STP and MIT? MIT is really what is confusing me, I do not see a reason to use it.

Say I am about to go long on stock xyz which is currently $50. I think it will go to around $55 but to make sure I don't lose too much in case it goes down. So I simultaneously place a limit order for 50.01 (or whatever) and I place a sell stop at $48. Correct?

Ok now this is where I get confused. Say the stock rises to $55 and I want to sell. Couldn't at the time I created the initial order just place a LMT sell at $55 to accomplish this? Or should I place a sell MIT order with a price of $55. I think these both will accomplish this correct? If not where am I wrong and what are the exact type of scenarios one would use a MIT order?