Can I place a stop loss and a limit sell at the same time?

I would recommend buying put options over stop loss (although what I would recommend even higher than either is not investing money you're not willing to lose in the first place), especially with cryptocurrency. A stop loss relies on the market being liquid enough to find a counterparty. In a panic, the price is going to plummet and by the time you find a buyer, you're likely to get far less than your stop loss price, and can easily lose more than if you had just ridden the panic out. With a put option, you have a counterparty locked in, and your strike price is fixed. And if you think a stop loss is a good idea, then probably a lot of other people are going to as well, which means that you'll all be bidding against each other, driving the price down even more. If enough people do this, a slight decrease in price can set off a crash.

Yes, as far as the market is concerned, you can submit a limit order to sell at a good price and stop-loss to sell the same asset at a bad price. I have done things like this in a professional context with no problem.

The only limitation you might have is whether the broker you are using permits this behavior. It kind of looks like yours does not. You can search for a different broker or look into a contingent action of some kind. That is, you can specify that if either of these trades executes, the other should be immediately canceled. You may have to submit them together in order to keep your broker's computer happy.

All this stuff comes down to what your broker permits so you should consider contacting your broker to find out how to do this.

This is sometimes called a bracket order and can be done for stocks. It is offered by some brokers, but not all. It does take slightly more sophisticated infrastructure for the broker to support, so not all of them might bother, especially in crypto.

As a note, if brackets are not supported but you have access to options, a vertical spread should provide very similar outcome to a bracket. Though, to truly benefit from the vertical spread, you would likely need to place a bracket order on the spread anyway.

TrailingCrypto is a service that works with many Cryptocurrency brokers and they offer a tool called OCO (order cancels order) that achieves exactly what you're asking for.

Here is an article describing it: https://www.trailingcrypto.com/support/article/oco-order-cancels-order