I think I understand your question.
Yes you can trade all from same account (not Forex).
Basically all are treated the same, you trade a "product" be it a stock, etf or futures contract. You always deal with a "quantity", the default is normally 1 unit.
You maintain a "watch list(s)" of symbols (never maxed out) and you can switch among them for your "real time data stream" and "real time streaming charts".
You can enter trades at least 2 ways, from an "orders page" which allows you to set up "conditional orders" or right from the "streaming charts" page (which I really like for entry/exit) when you just want to initiate a trade. Here you can set parameters such as buy/sell, quantity, market/limit, price. I like this because you have current last trade, bid/ask, b/a quantity etc. right in front of you as well as the chart. Thus, if you want to "split the spread" or do a little "duck shooting" by leading where you think things might go in short order, you can.
Anyway, I hope this helps.
Ox has been "Impeccable" in my opinion. I hope the CS buyout doesn't introduce any negatives.