Timon Schmidt - Yes, it is possible to query the Graph API using a bot in the Bot Framework. You can use the Graph API to get information about users, send messages, and much more.
To do this, you will need to authenticate your bot with Microsoft and obtain an access token, which you can then use to make requests to the Graph API. You can find more information on how to do this in the Microsoft Graph documentation.
As for rate limiting, Microsoft does impose certain limits on the number of requests you can make to the Graph API per minute. However, these limits are generally quite high and are unlikely to be a problem for most applications. If you find that you are hitting these limits, you may want to consider optimizing your application to make fewer requests, or spreading your requests out over time.
If you still need to make more requests than the rate limit allows, you may be able to negotiate a higher limit with Microsoft. This would likely involve entering into a contract with them and possibly paying for the additional capacity. You can find more information on this in the Microsoft Graph rate limit documentation.
As for sending proactive messages to users, this is also possible using the Bot Framework. You can find more information on how to do this in the Bot Framework documentation.
for general help with using the Bot Framework, you can refer to the Bot Framework documentation.