I have never wagered at an online casino, but I have a few comments.
First, I suggest that you cash out now and see what happens while you have a relatively small stake. I believe that the single biggest consumer complaint with online casinos is the inability to cash out. Some places simply won't pay. Others may take months. Of course, if one of them fails to pay you, your options are limited. Because the operation is probably located in Costa Rica or some similar offshore locale, you will have a hard time (a) finding them; (b) serving them with process (c) obtaining jurisdiction over them. Even if you are successful in obtaining jurisdiction, you will still face the problem of trying to obtain a judgment on what is probably an illegal contract: See unc.edu
The other problem is that even if the casino itself is "legit," they probably are using a third-party processing company to process your VISA card. Since the major card companies don't like doing business with offshore, online casinos (too many chargebacks), casinos and processing companies have had to get creative. Many processing companies are just as fly-by-night as their clients.
So, (although my best advice is to stop gambling for real on the internet), if you are going to continue you should test the payout system now and see how it works, while you are still in the black.