Well, I didn't know that you could route to individual exchanges under TDA. I hadn't looked in years, so I guess I'll need to read the software release updates. I've been in the business a long time.
A MM needs an edge to take an order so he won"t be trading at theoretical midprice unless under the exceptional circumstances his book is too big in some way somehow. But don't count on this last thing to happen ....
I suggest you search all of his posts under all of his user names, and make notes. Then search for riskarb on google and you’ll find he’s generously posted on many different forums over the years. Actually you may want to check the google+ forums first as google is about to close google+ and delete all the content. Reading options books gives the big picture how everything fits together and will answer many of your questions.
On TOS, it's really difficult to know what the bid/ask is at the time of fill. Sometimes I have the option chain open when I get filled and I think this is my best chance to see. Even still, though, the prices usually change over the next second or two and I figure my fill was a little bit off.
If you want to succeed at trading, then I suggest you be a lot more selective in what you believe than seeing a couple insightful posts and believing someone knows what they're talking about or has made any money doing it. No offense intended to you, destriero.
I've sent emails to TDA asking to show the NBBO on all orders, analysis, etc. Worse, single options show only the bid on sell and ask on buys. You can see the mid and NBBO on all if you hit edit after "confirm and send" You'll see (partial lol) NBBO when it takes you back to the "order entry" screen (after edit). They give you the mid and natural (offer) and vice versa. in any event, it's a moronic method of quoting. The client should not have to calc the actual NBBO on the complex order.
I've seen that bar incorrectly report for single options. I've used the stated mid only to get filled and immediately see the bid/ask reflect a different midprice leaving me to think I should have looked at the option chain initially when selecting the price. What I would like is, as part of the trade alert, a statement of bid/ask at the moment the trade was filled (just like we get a real-time report of underlying price and IV). They could even report the bid/ask of each individual leg.