If you use another URL shortening service, whether your Associate ID is included can really vary from service to service. Generally speaking, when using an outside URL shortening service, your Amazon Associate ID must be included BEFORE you shorten the URL. You should be aware that some services will add their own Associates tag to the shortened URL or remove your Associates tag altogether. Also, please be aware that some shortening services use their shortened URLs to frame the Amazon site. If the links you get from any service do this, or otherwise do not resolve to the www.Amazon.com domain in the address bar, you cannot use them in the Associates Program and you will not earn referral fees from those links.
The online lead generation is a multi-billion dollar industry. Done right it can be far more profitable than many imagine. Everyone that I know that is in the business and knows what they are doing, for the most part, does 6-7 figures. While that's a huge range, much comes to one's ability to scale and effectively build / manage the infrastructure needed to scale.