The Sonic IDW comics are indeed canon. They build upon the existing Sonic lore and expand the story in new and interesting ways. Although they may have some creative interpretations, they are accepted as part of the official Sonic continuity.
It's a bit of a mixed bag. Some IDW Transformers comics fit neatly into the overall canon, while others might have elements that are more open to interpretation or might not be fully accepted by all fans and official continuity.
Overall, the IDW Sonic comics have their merits. The character development and plotlines can be engaging, but it might not be everyone's cup of tea. The art style varies from issue to issue, which can also influence your enjoyment.
The status of Transformer IDW comics as canon can be a bit complex. Sometimes they fit seamlessly into the overall Transformer universe, while other times there might be some contradictions or variations. It really depends on how the franchise decides to incorporate them into the broader narrative.
It's hard to give an exact number. The number of IDW Sonic comics keeps changing as new issues are released. You could look up recent comic listings or ask on comic enthusiast communities for the latest count.
In general, the IDW and Archie Sonic comics are separate entities. They have different character developments and plotlines. There might be some shared elements, but they don't have a direct connection that ties them closely together.