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.
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.
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.
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.
It's important as it expands the Sonic universe in a new visual and narrative form. It can introduce new characters, storylines, and explore different aspects of Sonic's world.
In a Metal Sonic x Sonic Fanfic, the action and adventure aspects can be really exciting. Writers may create new challenges for Sonic and Metal Sonic to face together or against each other. For example, they could be forced to team up to defeat a greater evil that threatens their world. This kind of fanfic also gives a chance to delve into the emotions of the characters. Metal Sonic, although a machine, might show signs of evolving emotions or at least a form of artificial intelligence - based loyalty or rivalry towards Sonic.