Guide to feeding?

How do you know what to feed your baby and at what point they are ready for larger quantities or to try new things?  I feel like I'm clueless about feeding.  I'm going to ask the Pedi when we go this week, but was wondering if there is something others use as a guide.  My daughter is 9 months old and has one tooth half way in and another that just broke through, both on the bottom.  She is now only drinking formula as of her 9 month bday and has 2 x 2nd stage baby food containers a day.  I've only given her the fruits and veggies so far.  She also has puffs and sometimes oatmeal mixed in with the baby food.  She eats twice a day, but it seems to be making her drink less formula.  Is that ok?  How much formula do they need at this point?  She's tiny for her age, but has started to put on more weight since switching to formula and eating solids (around 16 lbs now).  What foods can she eat at this point?  I'm worried about her choking, but she does chew with her gums.  How do you work in foods other than baby food if they go to daycare during the week?  Thanks!