I can only address your first concern: My DD showed little interest in solids when we introduced them at 8 months, and continued to have very little interest for quite a while. Sure, she would eat a bit here and there, but she was certainly not getting any decent calories in solid form until well past 1 year. Beyond age 1, she began to enjoy drinking from the baby food pouches, and that helped her transition to more solid foods. I was concerned enough about her eating, though, to have her evaluated by early intervention at 19-ish months. At that point she was showing more interest in solids, but tended to spit most foods out instead of swallowing them - texture issues. To make a long story short, by age 2 she was more or less a normal eater. She still doesn't eat a ton, but she eats a variety of foods, healthier than most of those I see her peers eating. She never really dropped in percentiles or lost weight during that second year when she wasn't eating well and was mostly beyond milk.
Is there concern over baby losing weight? Or is the concern ONLY about the lack of solids? If it's the latter, I would say definitely not to worry about it.