Proto-Indo-European. (There is also a new theoretical language called Pre-proto-Indo-European).
There is no Proto-Indo-European language group. Proto-Indo-European, or PIE, is the hypothetical root language from which Indo-European languages today (and others that are extinct) descend.
Yes it is. Urdu belongs to the Indo-Aryan branch of Indo-European languages.
You can attach the prefix Indo- to it to make the word Indo-European.
No, Arabic is not and indo-european language.
Yes. Persian is an Iranian language within the Indo-Iranian branch of the Indo-European languages
Yes. Sanskrit is part of the Indo-Iranian branch (or more specifically, Indo-Aryan) of the Indo-European family. It contains similarities in terms of vocabulary that is found in many European languages.
John V. Day has written: 'Indo-European origins' -- subject(s): Anthropometry, History, Indo-European languages, Indo-Europeans, Origin, Proto-Indo-European language
No. Indo-Iranian Language
Welsh is an Indo-European language; a member of the Celtic subgroup.
See related links for a map of the Indo-European language tree.
No. Only certain languages in Europe and India are considered Indo-European.