There isn't anything in the Gerber baby food that's "bad." If you look at the labels, they usually just contain the fruit or veggie and water (although some of the older baby foods have sugar, so watch out for that). I made most of Tyler's food, except for a few things, but the reason was just because there was more variety of foods he could try if I made them. If you do go with store bought, there's absolutely nothing wrong with that and no need to feel guilty. Just read the ingredients to make sure there's nothing added.
Most parents introduce finger foods around 7-9 mo, but really just depends on your baby. They don't need teeth because they don't actually chew anything until they get molars later on. They "chew" finger foods and lumpy solids by mashing them against the roof of their mouth with their tongues and gumming them.