What are the difference to sell houses with realtors and company’s “Cash for house” ?

I need to know what is the difference to try to sell my own house with a realtor agent and by my self using the companys (cash for house) the price of the house will be low?, the time to try the sell is long or short?, the amount to pay for the transaccion will be the same? or whatever difference between boths way to try sell my home.

houses short selling, do banks tend to approve this?

I have been looking (online) at some houses in an Austin Texas neighborhood.
I have noticed multiple houses say “short sale, bank approval required”.

I know this means that the house is selling for less than is owed to the bank.
Do banks tend to approve these?
Should I be weary of buying such a house?

These houses also seem under-priced compared to other houses in the same neighborhood that are the same size.

We have to houses, one is rented out and we decided to sell?

the agent suggested go for short-sell where we are living and sell the investment property. According to her, she will not get any money from the short-sell but in the other one, we have to paid her and the buyer’s real estate agent. Is that true?

What will happen to all of the houses the banks will not sell in short sales ?

I have two houses but i want to keep one and do a short sell in the other house can i do this?

how is this going to affect my credit and for how long.