Hi
You poor thing. I think you are worrying yourself into a frazzle. Reading it I would say yes there are some autie things on there BUT ALL CHILDREN DO THOSE THINGS. For example, my eldest (who has autism amongst other stuff) never ever ever lined anything up and although enjoyed Thomas wasn't obsessive about it. My youngest who doesn't have anything (apart from naughtiness and cheek ) lined up trains, carried his Thomas engines about with him and played Bob the builder and cars till blue in the face. My eldest made eye contact and still does but does it on his own terms. He smiled at bang on 6 weeks and hit all his mile stones.
As someone has mentioned ASD is HUGE. It is a landscape of difficulty and everyone has their own indvidual landscape with different hills/valleys/etc. A lot of very young children do fit in with the autistic type spectrum because that is how toddlers survive - self obsessed, interested in their own stuff, lots of repetition to learn etc etc.
The only alarm bell for me that is the same with my eldest at the same age is the leading you to things he wants rather than saying the word. This can also be indicative of Speech and language disorder or another communication disorder and might not be full blown autism although they all have shades of grey there.
What to do: Lots and lots of over the top imaginative play. Make it silly, pretend you are jumping over waves in your living room or that your bed can fly and that you are seeing polar bears and flying round the world. Rig up a tent with old sheets and backs of chairs. Do lots of pretend play with playdoh and saucepans, cups, washing up etc etc - link it in with what you do in the kitchen so if he doesn't have a huge imagination then he can link it to something. Just talk all the bloody time to him and one day, I promise you, you will wonder why he won't shut up and you will be writing on here that your son never stops talking and how to you get him to stop (it's own set of problems believe me).
Don't worry AT ALL about the baby. Enjoy her. If they've got difficulties well they've got them. Its a mountain we wish we didn't have to have but at least its an understandable mountain and one that has been climbed by many people. Your little boy sounds lovely and a helluva lot like many other almost two year olds. However, if you have a hunch then you are right to go with it because the earlier you get therapy and help the better. He is wanting to communicate with you and is reacting to the world he is living in which is good.
I wish I could have met my 14 year old when I was going through this when he was 3. He is the nicest child on the face of the universe and yes we sometimes cling to the mountain face but HFA is not the worse thing in the world.