Im so sorry to hear Thomas died, Carrie. Praying for Han and all the family and for you. It's such a difficult time of year too. 
Welcome originalmavis and lumpy.
Orchid, praying things go better today with dh. It sounds really tough.
Continuing to pray for you Sparky
Bes, praying that ds will get on well on the trip and feel calm.
Bes did a great job of explaining the holy spirit:-) the bible makes clear that the father, Jesus and the spirit were there before creation (the earth was timeless and void and the spirit of God hovered over the waters; in the beginning was the Word etc) - so God was and is always separate from time. It's mind blowing really!
It's hard to explain to a small child about Jesus being ageless, you can show something similar by talking about how they are separate from any worlds they create (eg happy land, lego etc) , they do not live within the constraints of that world but it's certainly not a perfect example as it brings up questions of control etc.
I think keep it simple and remember children don't have to understand everything and often accept things in their own way which is often far more faith filled than us adults! Say that Jesus, the father and spirit are all God, different parts like BES' analogy, and they have different ways to help us. Jesus saved us and is now with God but told his disciples he left the spirit as a comforter. To a child this can be a simple and lovely thing - that God loves them so much he wants them to feel happy inside and the HS helps them, and also helps them see what is not right (conscience) - so reminds them if they are not being kind or whatever.
When a child asks how old Jesus is, I'd say he doesn't have an age because he is all around, always has been and always will be and loves you very much.
It's hard though- but children often seem to get it regardless of what we say!!