Hi Tractor serial number will be engine number Stamped on a pad on the block under number one fuel injector on front right side of block. Hopefully it still has the right motor fitted as if not you got to decode casting numbers on a few components to verify age. I guess the back hoe and loader would have it's own serial number tags fixed on.
For hydraulic adapters usually any tractor and machinery dealer locally or a bearing and hydraulic supply company carries them , You will need to tell them what the thread sizes and type are, or take the parts you need to join together to them. They will then either have the part on the shelf or get it for you. there are hundreds of different adapters out there for hydraulics. Regards Robert