Hi Jared. Some prefer to start them early indoors, but I prefer to direct sow beans, corn, and squash. All 3 germinate quickly and have large seedlings that are easy to weed around, and all 3 prefer warm temperatures. I usually sow those in late May or early June.
Tomatoes and peppers are good candidates for starting early indoors. Peppers always grow slower for me, so I'd start those 6-8 weeks before your forecasted last frost date. A lot of folks start peppers and tomatoes at the same time.
To best know what fertilizer to use I'd recommend getting a soil test. That way you're not adding unnecessary nutrients and you know how much to use. Without knowing I fertilize very lightly- better to err on the side of caution. I prefer compost and organic fertilizer for food crops (I usually find some to choose from at Lowe's).
