There are quite a few posts on this, but I would like to clear some things if poss. Is it that I am supposed to send all my fleet including all the resources I can to somewhere & back while I am not logged on? If so I am never to protect my planet? Do my infrastructures not get damaged or my solar sattlelite thingies? I have some defenses built though.

Also are small shields worth building at all, if so why are there more than one? Do they layer like onions?

In the scheme of things, shields are worth having and are so cheap, you might as well get them. Defences depending on what you have deter other players from attacking. If you have minimal defences, then it will deter players of a similar size and score as yourself. Your solar sats will be destroyed if attacked by a stronger player, depending on how many you have, they do leave a debris field, if large enough the attacking player will collect that also. Your structures on a world and a moon are permanent. They cannot be destroyed, apart from the ones on a moon, they can't be destroyed in themselves, but if the moon they are built on is small enough to be destroyed, all structures built there are also destroyed! Your planet CAN be protected, if a: you have the biggest fleet that nobody wants to mess with, or b: your have mega stooooopid amounts of defences, I'm talking massive figures here! Try to get moons as soon as possible, if you launch any fleets, whether to fleetsave or attack, always try to do it from a moon! There is an excellent fleetsave guide in the forums, I really recommend that you either read it, or copy and paste it to your notes in your player menu.

I did read that fleet save guide was helpfull. It just seemed strange that I should send my fleet away. Thanks for shield advice, is it though that they stack like onion layers if you buy more than one, in addition to leveling them up?

You can only buy one small shield dome and one large dome, they will give your other defence some protection, and I agree with mightyoz get moons asap the bigger the better, try to get at least one moon at like 9.8k in diameter, that way you can use your moon and avoid being lanxed on your planet by the bigger players, let me know what server you are playing and I will help you out best I can

I am on standard. Thanks