Verizon only has one active plan now, simply called the Verizon Plan. If you can't, or don't want to add a line to your current plan, you'll be forced onto a VP. It's $20/line for line access, then you just pick your data amount which has its own price points.
Since you have a 2 GB/line plan now, you may want to start by looking at the medium 3 GB plan for $45. The Verizon plan data is shared, so that may or may not be enough depending on your usage. The next step up is the large for $60. Value wise, the XL and XXL are better, with 12/$80 and 18/$100 respectively. Any plan XL and above just got a promotion adding an additional 2 GB at no charge for the life of the line.
Many people have had success with trading in throw away phones. I personally used a $14 Tracfone that I bought specifically for the $300 new line credit. They may have recently enacted a minimum three months active on the new line to avoid having the $300 charged back, but it's otherwise hassle free. The $100 off is just a general sale, not requiring anything special.