"So am I OK using two browsers on this laptop?"
Use as many as you like - I currently have four browsers installed.
"why is there not a simple download button SPECIFIC to the programme you want?"
Bear in mind that everyone has a living to make, and software providers will often try to get you to pay for a more enhanced version of a product rather than the stripped-down free version. There's nothing wrong with that - it just means you have to be prepared to drill down a little to find what you need.