If you assign a bot to your platform do you have to use two coins it buys and sells between, or can it buy and sell one as the price fluctuates?
I think you can program the bot to buy as per an algorithm. However you will need to provide the starting capital, in terms of fiat deposits or crypto deposits to allow it to trade.
Usually staying on one pair of assets is done but this depends on choice of the trader. It is best if you analyze charts and see which ones you want to focus onto and predict are going to move a lot in the market. Day traders are running bots mainly buy/selling a specific pair, but I dont have experience not interest in bot-mediated trading so you should research more on this yourself.