1- Can we consider the compilation of the Quran at the time of ‘Uthmaan ibn ‘Affaan, may Allaah be pleased with him, a good religious innovation?
2- Is there a Hadeeth where the Prophet, sallallaahu ‘alayhi wa sallam, stated that there is no good innovation in religion?

All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

The definition of religious innovation does not apply to the compilation of the Quran at the time of ‘Uthmaan ibn ‘Affaan .

A religious innovation is any act that was not practiced by the Prophet .

The scholars set two condition for an act to be an innovation:

1-   There was a need for it.

2-   Nothing prevented him, sallallaahu ‘alayhi wa sallam from doing it.

Therefore, compiling the Quran during the era of ‘Uthmaan was not a religious innovation because during the time of the Prophet there was no need to compile it. However, when the Muslims spread and increased and the non-Arabs embraced Islam, the need arose.

Other scholars clarified saying:

1-   Defining a certain limit, like vowing to fast while standing.

2-   Setting a certain fashion of performing a legislated deed, like mentioning Allaah collectively.

3-   Performing a deed in a specific times like fasting the mid of Sha’baan.

With regard to your second question, there is no narration with this wording, nevertheless the meaning of what you said is correct. However, if we consider the meaning linguistically, then the meaning is not correct, since an innovation in the linguistic  sense, refers to any new thing, in such a case the compilation of the Quran and performing the Taraaweeh prayer in congregation can be described as a good innovation, as ‘Umar described it.

Allaah Knows best.