Ok heres a question. If i have an oldblood and give him light armour that means I couldnt give him lets say glittering scales but could I give him lightarmour and the enchanted sheild?
I don't see why you couldn't take both, but Glittering Scales counts as light armour anyway - so why would you do both? Unless you mean can you ass the 6+ save from glittering scales to the save for light armour to make 5+ save, in that case no you can't
I believe you can take the dragonhelm as well as LA to get another point of armour for your OB. You can also take a cold one as CO + LA = 1+ AS for OB without use of magic item allowance, but have to suffer the disadvantages of riding a CO.
The limits on armor only applies to multiple magic armors or armors of the same "slot". You could take the Dragonhelm, as well as light armor, and a regular shield. You could take magical heavy armor and a regular shield, but not a magic shield. You could not take light armor and another piece of magic armor that counted as heavy armor or light armor.