2.If you want to purchase TCH with BTC, choose BTC Market and input TCH in search box. Then you can enter to transaction page by clicking TCH/BTC pair.
3.You could trade on CoinTiger via market sell/buy and limit sell/buy. If you choose market sell/buy, you could set the price that close to ask1/bid 1 to sell/buy. However, you could also trade via maket if you wanna to make transactions immediately.
Remark: A stop-limit order will be executed at a specified (or potentially better) price, after a given stop price has been reached.