1) If you can acknowledgement / copy of complaint it is fine, even if it is not there, you can give notice for partition of properties to your uncles and aunts.
2) File suit for partition of properties by metes and bonds, along with an application seeking injunction against all legal heirs restraining them from changing nature / alienating / creating third party interest in the property.
3) All the legal heirs of your Grand Father (GF) are entitled to equal share in the property unless (the other properties are Gifted / bequeathed by way of Will by your GF to you uncles).
If the same is distributed among them, all the properties are amenable to partition.
4) No, Limitation does not apply for filing suit for partition.
5) As stated at (1) after issuing notice calling all of your uncles & aunts for partition, you (your mother) can file suit for partition and seek her share.