Take heart!! I have had 4 children, (the baby is 2 mos now) and I still hear what I should and shouldn't be doing. Unfortunately I don't have a reply for the unsolicited comments except to smile and say, "Well, they're all healthy and happy so I must be doing something right!" That lets them know that you get the advice but you are confident enough to know that you're making good decisions for your children.
As for solids, I have always started about 4mos, but with our new baby, I am thinking of holding off until he is 6mos, we are planning on having a garden, and I can't wait to give vegetables we have grown ourselves. I made babyfood when the others were babies but I started solids with them earlier. I would like to see how BF exclusively goes with this one. If I see he is looking to try our foods, then I will introduce sooner but I would like to give this a shot. This is our last baby and I want to do things differently. Besides, I am home now (no longer working) and BF exclusively (no cereal or juice until at least 6mos) seems like the right thing to do this time around. You learn with every baby!! I feel like now that this our last, I just might be getting it right!! I am sure when my DD is grown (only 6 now) I will have lots of unsolicited advice for her!!
good luck and I am sure you are doing a great job!!